Dear Biker,

  • Are you tired of cold starts? Need to raise the throttle everyday to get the cold engine running?
  • Does someone have the same bike as yours and are you tired of losing to him in drag races?
  • Suddenly, the fuel efficiency has reduced after a service?
  • Has the mechanic has screwed up your tuning?
  • Engine gives hiccups when you open the throttle?
  • Or your bike is just missing that smooth acceleration whenever you want?
  • Or your engine overheats even if you did not race too much.

May be the following will help you in tuning your mean machine for optimal power delivery and best fuel economy. This guide aims at tuning the fuel/air screw to give you an optimal air-fuel mixture. An optimal mixture gets maximum performance from your machine.

Getting The Basics

I am assuming that you know driving very well and have completed at least 1000kms on road. If not, then you are too amateur to read this guide.

Every bike has a engine (motor/mill/muscle) and a carburetor (breathing system/heart) 😉 – Yeah I know that. My point is, I assume that your engine is in perfect condition. That is, there is no oil leaking from it etc etc.. The next assumption is that your engine is not DEAD. You know where your engine is and where your carb is 😉 and you have a screw driver/blunt knife with you. Your machine must have finished at least one service ~500kms or more. Also make sure you do not change the fuel type while tuning i.e. Power, Speed, Extra premium, normal unleaded etc.

This Guide Applies To

All the single cylinder bikes, 2 stroke or 4 stroke having a carburetor. Tachometer is very handy and a must for a newbie or the tuning process will be very slow or painful or imperfect.

Disclaimer: Though whatever I have written here wont do any damage to your machine, finally you must not blame me for whatever happens. I am here to help if anything goes wrong.

So Lets Get Started

Warm the engine nicely. Go get a ride around the town. Speed nicely at least upto half the top speed of the bike. Drive at least for 10-15 minutes so the engine system warms up nicely or you’ll get a bad tune. Do not just leave the engine idle and start with process. I mean it. Ride the bike.

Now that the engine is adequately heated up, you are ready to begin with the process. You can select a place far away from the city or your residential area so that you do not disturb the tired, sick, disgusted, old people or babes (babies) living in your colony. You are likely to be shooed away from them when you are at a critical point. You may choose a place near your girl friend’s house just to impress her! Put the bike in main stand and get hold of your screw driver. That is all you need, together with your eyes, brains and ears.

Searching the fuel/air screw… The above mentioned screws are responsible to adjust the air-fuel ratio which forms ‘food substance’ for your engine. You can relate it to our human body, where proteins, carbs, fats, water etc all are required in appropriate proportions with respect to each other for good strong body.

There is another screw which sets the idle speed of the machine. This screw is not related to pickup or mileage. It just sets the engine rpm at ’’idle’’ run. 2stroke machines have an Air screw and 4 stroke machines have a Fuel screw. I hope you note this VERY well. Air screw is located on the carb away from the engine. [ Engine – Carburettor – Air screw]

Fuel screw is located on the carb but its near the engine. [Engine – Fuel screw – Carburetor]. If the make of your carb is Mikuni (Pulsar, Yamaha, Fiero) the fuel/air screw probably will be of brass (golden colour). If you fully unscrew this screw and take it on your hand, you will see a needle like tip.

Idle screw is closely linked with the throttle cable. Idle screw can be turned by the hand. Screw driver is not essential for it. Finding these screws are very simple. If you still cannot find the air/fuel screw, ask your mechanic or I can help.

Ok now what? Apart from the above difference I gave between Air and Fuel screw, there is one more major difference. Fuel screw turned in (clockwise) gives a lean mixture and turned out (anti-clockwise) gives a rich mixture. Air screw turned in gives a rich mixture and turned out (anti-clockwise) gives a lean mixture. Lean means more air, less fuel. Rich means more fuel, less air. This ends the basics.

Getting Things In Action

Turn the idle settings screw so that rpm reaches about 3000 rpm. Now tune the air/fuel screw to make the mixture leanest as possible. Please refer to the above whether you must turn the screw clockwise or anti clockwise.

As you make the mixture leaner, slowly the engine RPM decreases… Go on doing this until you have put the fuel screw to the leanest possible point. At the same time, ensure that the engine does not stall, by turning the idle-screw.

Tough huh? You’ll get used to it 😉

OK the engine is running and the mixture is lean. If you notice from the engine sound OR if you see the tachometer, the engine RPM will not be steady at this point. Now very slowly start turning the fuel screw anti-clockwise, quarter to 1/8th turn at a time. You will notice that the RPM increases slowly and steadily. Again, do this very very slowly. Also count the total number of turns as you wind out the screw.

You’ll notice that when you have turned it to about 3-4 full revolutions, the engine RPM slowly becomes constant. It is this point that you must stop screwing more. This probably is the optimal setting for your engine.

Further on, try turning the screw even more and more to 5-7 revolutions and you’ll notice that the engine RPM will slowly decrease. When this happens, you are just putting in a too rich mixture in your engine. At this point the engine loses all the fuel efficiency and the mixture is not optimal. Repeat the process about 2-3 times. Count the revolutions each time and get the setting which you feel is correct.

OK the engine is humming perfectly, now what? Decrease the idle setting screw to about 1000rpm in the tachometer. When the engine slows down, just twist the throttle. The response should be crisp and quick. It should not give any hiccups! Try shutting off the engine and restarting. The engine MUST start in a single kick or self with out giving throttle. If this happens, the setting is ok. Now get a ride and you’ll notice the difference for good or bad 🙂

You’ll immediately notice change in the engine sound and the throttle response. Your engine can become more smooth or harsh. Another important point is, Ride and Feel. Always take a ride and get the feel of the bike in each gears, check the response and the engine sound. You’ll quickly come to know once you get the feel of the bike that you want to make the mixture rich or lean.

It may take a few iterations before you fix a setting as permanent. Try calculating the mileage per liter and tally it with your setting and the feeling you get.


“Ahwini, I messed up my tuning because of you!”

Here are some symptoms and their quick solutions:

  • Engine dies while tuning.
    Try the process all over again. This time set the idle screw higher/faster.
  • Engine gives hiccups while driving, specially while in higher gears.
    May be the mixture is too lean. Try again.
  • Engine heats up.
    The mixture is too lean or too rich. Try again.
  • Whenever I race up the engine, the rpm increases fast but very slowly comes down to idle.
    The mixture is not optimal, probably towards leaner side. Try again.
  • Too much low end torque and the engine sound is very beaty/thumpy.
    You’ll face a low mileage surely, when you drive below 40kmphr. You have tuned on the higher/richer side.
  • I have doubts or I have other problems.
    Why don’t you put in a comment?

I hope this helps! Take care. Any comments are invited.

Ashwini Kumar

Click To Expand


  1. Thank you deepak, For publishing article on your website, i hope it will be usefull to you.

    @ kabi tuning does not effect engine life, but improper tuning will effect mileage and performance.

  2. Excellent article, exactly when i was in need of it. I want to try this on my Uni coz HMSI people has screwed my Uni’s carb its not giving mileage or power.

  3. this job should not be done by us , it should be corrected by a authorised service men dont act so smart and make the machine cry …

  4. I have the new CBZ-X, oct’08 model. Have completed only 3100 Kms and 2 free services bcoz of my frequent outstation job schedule.
    1.RPM was at 2500 prior to first servicing, after that has been resetted to 1200.
    2.Used Power b4 first servicing, reverted to unleaded petrol and has been using the same.
    3.The bike gives hiccups if driven at slow speed(20-30KMPH)in higher gear(3rd/4th)in heavy traffic.
    4.Mileage around 40KMPL is achived by me at max inspite of the fact that I had driven with utter care with least use of brakes & cluthes and speed of 40-50KMPH for test purpose.

    PLzz advice whether my bike needs any resetting or any sugzz to increase my mileage to around 50KMPL

  5. @ shubh and rajesh

    i think your tuning is set either too lean or too rich,

    i give a thumb rule which will let you know if your carb is tuned properly or not.

    just open your spark plug ans see the color of electrode,

    if it is dark black then mixture is too rich, if it is light gray then it is set too lean.

    the color of spark plug should be just black, light brown, but not black.

  6. Ashwin Pls try upload a video. bcoz i would make a better demonstration.I have an 2007 APACHE RTR. At first i’ve got good milleage about 50-53kmpl after 1st service my milleage has been dropped to 40kmpl still i have the same problem. I will ride my bike max @ 70KMPH. How can i increase my milleage along with good power?. THANKS for the nice post.

  7. That is a very detailed article on improving performance. I am sure many will benefit from this considering that most people are not satisfied with the performance of their bikes.

  8. @ anil

    i think the service centre guy has tuned your carb to rich mixture, they always experiment wid other bikes.

    i think there is no need to upload video, u can easily find the carb easily and can see the bronze color screw this is one u have to turn it clockwise or anti clock wise as per your needs , but make sure when u do so your engine should be warm., thank you, im definetly sure many ppl will found it to be very useful

  9. anil i think the service centre guys have tuned your carb to rich side, get it correct as per the article.

    @, thank you, i too think this article will prove helpfull to the needy!!!

  10. Shubh,
    3.The bike gives hiccups if driven at slow speed(20-30KMPH)in higher gear(3rd/4th)in heavy traffic.
    ^ above mentioned point is the biggest symptom of low avg.
    CBZ-X is a high RPM engine with low tork compare to RE product which low RPM machine. Riding 20-30Kmph that is also in higher gear will definitely kill the AVG. I think just change ur riding pattern before touching the carb. 20-30 kmph means u need to be in 2nd gear or almost switching to 3rd depends on load. Besides droping in avg depends on many other factors, not only carb setting.
    1.Secondary Chain setting 2.Petrol quality 3.Riding Pattern 4.Clutch Setting 4.Proper Servicing (Time To Time) 5. load carrying type 5.Petrol quantity given by pumps 6.Single hand or Multihand vehicle 6.If mulithand then again type of riding 7.Road condition etc.. etc.
    when you tune the carb. the exhaust should give u moisture feel with exhaust gas. Sometimes u can feel chilled carburetor body. sometimes u can see water dropplets from exhaust tail end.

  11. hey ashwini, i am not able to find the fuel screw in my mikuni carb(Pulsar 150). If possible can you please post the photo of the location of fuel screw in mikuni carbs.

  12. neel, the fuel/air screw is on the side where we have the fuel cock lever.

    see u straight and u will find a copper/bronze color screw,

    @pravin, yes these are applicable to all.

  13. Hi Ashwini excellent article.Thx a lot for helping out Indian Bikers by sharing your knowledge with us.

    I have a unicorn 2009 model , but Iam not able to locate the fuel valve , could you please help me n finding it.

    Thanks a lot again for all the help.:)


    THANKS FOR UR FEEDBACK, fuel/air screw is on the side where we have the fuel cock lever.

    see straight below the fuel cock and u will find a copper/bronze color screw,

  15. Neat explanation,props! 🙂
    but i got an issue:
    the tube thats below the carb and the air control screw is let loose in my Apache RTR and whenever i try to adjust the screw the fuel starts leaking from it :-/

    *iam not sure but i think the tube went into the stock air filter assembly before i replaced it with a K&N*

  16. thanks for article
    i know about these screw adjusting before but didn’t tried any thing like that
    i had myth that once any mess up had done its hard to get back to previous settings is it true
    i wish and piratically think its not correct. right?

  17. all the settings(clockwisw-anticlockwise) are explained in the article, pls go thru it. it is applicable to all types of carbs.

  18. hi nice info. M having a fz wid CV carb. a few days back service centre guys fu**ed ma byk for improving mileage i was getting 35 for speeds of 40-50. then after service pick up dropped n mileage was still same. i tried to tune on myself using above content. i turned to leanest possible mixture but at dat mixture also rpm was almost stable but power increased . engine became a bit harsh. but mileage is still same. other people are getting around 44. pl help me.

  19. harshit

    i think ur bike is getting very low mileage, see u must understand that it is not that when u make setting leanest, then only when u get the max. mileage….

    u have to get the best setting not rich and nor lean.

    what u do u make settings again using the above information, make sure engine is heated up, and after tuning setting ride the bike and feel change, and after driving for 2-3 km open the spark plug color and the color of spark plug must be brown or nearly light black. the basic rule to know if ur bike is properly tuned is that when the color of spark plug is very light black but not very black.

    after u get that color on spark plug and still ur not getting good mileage then u better see the yamaha service centre and get ur air filter clean.

    hope this help you.

  20. Ashwini: harshiti think ur bike is getting very low mileage, see u must understand that it is not that when u make setting leanest, then only when u get the max. mileage….u have to get the best setting not rich and nor lean.what u do u make settings again using the above information, make sure engine is heated up, and after tuning setting ride the bike and feel change, and after driving for 2-3 km open the spark plug color and the color of spark plug must be brown or nearly light black. the basic rule to know if ur bike is properly tuned is that when the color of spark plug is very light black but not very black. after u get that color on spark plug and still ur not getting good mileage then u better see the yamaha service centre and get ur air filter clean. hope this help you.

    tks for the info …..i have got my air filter cleaned already ….i’ll try what u said …..kindly tell me how to ckeck the color of the spark plug…

  21. harshit,

    just use your tool kit supplied wid bike and open the spark plug by removing spark plug wire and open spark plug using the spanner in tool kit or else go to a local mechanic he will guide u.

  22. @ BARANI

    1. the tube thats below the carb and the air control screw is let loose in my Apache RTR and whenever i try to adjust the screw the fuel starts leaking from it :-/
    A. I think u r tinkring wrong screw, I think u r opening float chamber drain screw. Both the screw looks very much same.

    2. *iam not sure but i think the tube went into the stock air filter assembly before i replaced it with a K&N*
    A. The tube u r talking about is drain pipe which goes to down side not to air box. Air box is connected with 3 pipes.
    a. Main air intake.
    b. Air induction System. Intake “oxygen molecule for Emmision”
    c. Crank breather.
    Besides after putting K&N I think u forgot to put crank breather supplimentry filter.
    The AF screw is always on the LH hand only bulls has got RH side AF provided if the engine is CI.

    Please mention your bike so Ashwini will help you.

  23. I Have A Doubt. Please Clear It.

    I Hav Set the rpm at 3000

    then turned the fuel screw to leanest position(the rpm goes down a bit, It drops from 3 – 2)

    After this am I supposed to set the rpm to 1000 makin sure that the engine doesn’t stop or shall I start turning the fuel screw till the rpm reaches to 3000.

    Please Clear It.

  24. Hi, Today I tried the procedure mentioned by Ashwini.
    1. First I rode my Pulsar 180 for about 5kms taking the speed up to 50kph whenever I got Chance.

    2. Then I parked the vehicle on Centre Stand and raised the Idle rpm to 3000rpm (Tachometer Indicated).

    3. Then I turned the Fuel Screw Clockwise Fully until its tight to make the mixture as Leanest as possible. The rpm decreased from 3000 to around 2000. But the bike did not stall inspite of the Fuel Screw being Full Tight. “HOWS THAT?”

    4.Then I slowly started to turn the Fuel Screw Anti-clockwise. The rpm started rising. Then at a point it became constant (Not Constant Exactly, but it was varying between 3750-4000 rpm).
    As Ashwini had mentioned that “Further ON, TRY TURNING THE SCREW EVEN MORE AND MORE TO 5-7 REVOLUTIONS AND YOU WILL NOTICE THAT THE ENGINE RPM WILL SLOWLY DECREASE. WHEN THIS HAPPENS, YOU ARE JUST PUTTING IN A TOO RICH MIXTURE IN YOUR ENGINE”, I did not see that the Rpm decrease even if I turned the screw more than 5-6 turns. The Rpm was around 3750-4000 even if I turned it more than 2 revolutions.

    1. How is that the Engine did not stall even if I closed the Fuel Screw Completely .i.e I turned the screw Clockwise until the screw went inside completely.
    2. The Rpm did nto decrease even if I turned more than 5-7 turns.

  25. faisal

    u are supposed to set rpm to 1000 rpm and make sure engine does not stall u can even set it at 1100 rpm for better cold starts!!!

  26. sudeep, its not necessary that bike will always stall when u are making it leanest. wat our aim is to make rpm go the slowest and as it become constant we should leave it, thats normal setting.

    the info i have submitted in articel is for cv carburettor made by keihin and mikuni.

  27. ashwini:
    sudeep, its not necessary that bike will always stall when u are making it leanest. wat our aim is to make rpm go the slowest and as it become constant we should leave it, thats normal setting.
    the info i have submitted in articel is for cv carburettor made by keihin and mikuni.

    But my question is that even after turning the Fuel Screw 5-7 Revolutions Anti-Clockwise, the Rpm did not start Decreasing unlike you said in the original post. That is bothering me.

    I am facing following Situation–
    After making the Mixture Leanest, as I try to Turn the Screw anti-clockwise, the idle rpm starts rising and after around 2 or 2.5 turns, the rpm remains varying between 3750-4250rpm approx. even if I go on turning the screw anti-clockwise for more than 5-7 turns.

    Ashwini, Could you please put light on this?

  28. sachchida:
    please tell me hero honda passion corburator have fule screw or air screw, i confused,

    Since HH Passion is 4 Stroke, it has Fuel Screw. i.e if you turn the Screw Clockwise it becomes Leaner and if you turn Anti-Clockwise it becomes Richer.

  29. ya even i face a prblm dat after idling the bike at 3000 rpm n turning the screw to leanest possible mixture rpm goes to 2000 rpm then wat shud v do start tuning or make the rpm to 1000 by rpm screw………if v shud start turning the screw 2 richer side then wen shud v stop
    1. is it till rpm reaches 1000
    2. or till rpm reaches 3000 again n become constant……

    plz guide ashwini……….also as u said i removed my spark plug cable n found black color on spark plug i didn’t open the plug. it seemed to b carbon deposit……so did i do it correctly n the color was not light nor dark. i cud jst c 1 single layer of carbon deposit…..

  30. @ ashwini

    My bike (fz) gives a poor city 36 mileage and poorer hiway mileage 32 …
    can this trend me from the carbeurettor

  31. I have a Yamaha FZR 1992. I was planning on putting a shorty exhaust on. Would this be the method I would use to tune it to not hurt the engine? Or would there be more involved?

  32. @ subiraj,

    ur bike is giving too low mileage, what u must do now, first u can tune carburettor as per my article and along wid this get ur air cleaner element cleaned and get clutch adjusted. or u can prefer overall service.

  33. Hi,
    I have FZ 16 and it gives me the 32 mileage in normal and 25 in riding condition can you advise!!!!!!!

    Is my carb tuning good? My engine gives slightly different sound from other FZ’s but gives great pick up and i can only reach to the top speed of 118 km/h though yamaha says 132km/h

    PLZ advise.

  34. @ raashid ur bike needs service and carburettor tuning as per the article.

    and about the top speed it is around 115-120 km for fz,

    132 is wrong figure for fz, only a karizma, pulsar 220, r15 or a bullet can reach such speeds.

  35. Thnx Ashwini

    I have done tuning of my carb as above and have just completed my 4th service and done 600 km after my 4th service.

    When i ride my bike for more then 30-45 minutes i always see moister on my carb and also on the tuning screw, why does that happen, is that the reason for low mileage or my carb is faulty?? I use unleaded petrol for my bike. Is Power or Speed fuel good for my bike?

    What if i install K&N airfilter, will it work?

  36. @ raashid, moisture from carburettor is normal, dont worry, and installing k&n filter will increase performance but decrease mileage, i will not recomend u to gor for k&n filters,,,,…

  37. @Ashwini
    I complete the steps mentioned by up to the Step of “START TURNING THE SCREW ANTI-CLOCKWISE AFTER MAKING IT THE LEANEST”. Then when I make about 2-3 Turns the Idle RPM Keeps Varying between 3800-4200RPM even if I go on Turning the Screw for more than 5-6 Turns. So I am not able to understand at which Point to stop Turning the Screw Anti-Clockwise.
    What should I do?
    Please reply.

  38. yes sudeep, the rpm can cary in some cases, after making it lean, turn anticlockwise 3 full rotations and u will see rpm getting constant if necessary get one more rotation, after that its ok.

  39. @ rahul,

    the article i have wrote is xclusovely for zma r …..

    i have tuned my karizma in same manner as written in my article and it is giving me constant mileage of 38-42 kmpl.

    kindly read article thoroughly…..

  40. Hi Ashwini,

    I’ve tried this on my FZ which is 5000km+ old.
    Here are my observations:
    1. With the idle at 3K rpm i turned the fuel screw to make it as lean as possible. But even after getting the screw to the tightest possible position, the engine was running smoothly at the same RPM.
    2. So i decided to make it richer by on anti clockwise turn and the went for a ride. there i observed that the pickup and engine response were more or less the same but, after releasing the throttle, the engine rpm came down quite slower as compared to before. So what do u advice me to do next??
    3. One thing i observed was that the rpm went close to 4K when i made the mixture rich by 6-7 turns.
    4. i am yet to check my spark plug as of now.But will do that.

  41. also i feel that the 3K rpm idle speed technique isnt working while tuning the fuel screw in the case of Fz.. Is there any other way of getting the ideal tuning.. (maybe a higher or lower idle RPM to be used for the tuning scenarion)
    Please advice.

  42. @ all

    i advice u all to pls first ride the bike for 5-7 km so that the engine is sufficiently warm for the tuning,,,,

    only then it will give u correct tuning,….

  43. Hi All,

    I finally got time to tune my 2009 Unicorn , its been a great experience with good results so far.

    Engine has become little more smoother than before and cold start the biggest issue with Unicorn’s is now much less of a issue.

    I from Bangalore … So I took my bike out to outer ring road and rode it for good 25+ minutes making sure engine is pretty warm , followed the steps as mentioned in this article.

    As most have noticed setting fuel screw to leanest possible mixture doesn’t stall the engine if idle speed is set to 3000 RPM before u start tuning , may be setting lower idle speed like 1900 RPM may stall the bike but I haven’t tried that.

    All I did was listen to engine sound when slowly making mixture rich ,, there are point when there is slightly higher increase in RPM and Engine sound ,, this is what I found on my Bike >> I set the Fuel screw to just one turn less from where engine really started making more sound than it did before for every turn.Its like there is more fuel being poured in to engine if I turn the screw further one turn and then engine sound remains same for next 4 + turns so I stopped and went back a little..I haven’t checked mileage but one thing I noticed is that I can ride the bike in 5TH gear at 40 ~ 45 Km/hr and bike wont start to cry or sound DULL as it used to slightly do before , BY THE WAY BIKE IS FITTED WITH K&N FILTER. THx a lot Ashwini. 🙂

    • Thanx ashwini
      it will very helpful for me.
      I have unicorn 2007 model 40000 kms crossed. I am riding in city limits. I am getting 40-45 mileage from last 2 years. But in a long route means in top gear riding i got a mileage of 75 in a speed of 80-90 kmph. I checked so many times. How is it? Is there any lose of petrol if i cover below 10 kms per day? I also checked if i ride 50-100 kms continuously in the city i got 50 mileage. How can i maintain the mileage 50-55 km within the city ? If i tried your tuning method will i get?

    • hi i also use a honda unicorn with k&n filter could you please tell me how many turn of the fuel screw did you turn

    • Hi Can you please help me locating the air screw in Unicorn 2009 Model. If I am not wrong, the fuel screw is located on the engine side of the carb which is accessible from the other side of bike (from the fuel cock end located at the lower left end of the carb), but i am not able to locate any air screw.

      PLEASE HELP as I am struggling for tuning from past one year as Service center mechanic has messed it up once and I keep trying to tune it but it not able to get RPM steady.

      Awaiting your response

  44. @ ASHITANK

    I thank you very much,,,,, i’m very happy that my article is useful to many ppl including you……

    i wish to add more meaning ful articles thru website…

    i also thank bikeadvice owner for publishing my article enabling many ppl to make good use of it.

  45. Hey nice article,
    By the way I own a Hero Honda Hunk. Every time the bike is set on the leaner side by the service guy during service.I can tell this because while it performs well in the city, it just gets sluggish after crossing 60 kmph. With pillion it becomes very sluggish even in city. I want to set it to a rich side.It is also giving hiccupps at high speeds. Please help me. I am not able to find the fuel/air screw for Hero Honda Hunk. Are there 2 screws? Or a combined screw? Where are they located?

  46. hi,
    I had purchased a hero honda passion plus bike in Aug. 2008.
    After 3 servicing, it started giving some noise as if some metal parts are rubbing from the front side(may be from engine).The sounds comes normally when i am driving at 30kmph. on 3 gear but disappears after getting through that speed.what may be the problem?
    Also let me know where will be the idling screw and the fuel screw in the carburetor?

  47. @ritu raj and zia

    the fuel screw is located on the opposite side of kick lever that is u look through the side where fuel cock is located and there you will find…a bronze screw/golden/bronze color.

    there is only one fuel screw and only one idle screw….idle screw is located on the rear side of carb,,,which is easily accessible.

  48. i have a avenger 200 >>the problem wid my bike is that its rpm jumps very quickly >>at 5th gear and 55km/hr the engine rpm is very high>>though avenger doesnt hv a rpm indicator ,,it gives a bad feeling and u can sense the rpm

    1 more thing i want 2 mention>>
    after my 2nd service the rpm problem was not der but after a day or so it started again>>
    plz help me wid dis

  49. Hi Ashwini,
    In your article, you wrote “while turning the fuel screw anticlockwise, the engine RPM slowly becomes constant. It is this point that you must stop screwing more.” …
    My question is that, at this point, will the engine RPM be at 3000?

  50. hi ashwini,
    pl. give me the complete constructional details of the carburettor of Honda Unicorn motorcycle with also give the internal details.Thanks.

  51. Dear Sir,

    Please let me know for ‘ Hero Honda Pleasure (no gears)’ fuel screw which side is Lean mixture and which side is Rich Fuel Mixture.


  52. Hats off to Ashwin, for this excellent Do it yourself guide. Although many people may be knowing this procedure, but one can’t find it so well documented anywhere else but here.
    Being a computer geek (have a bit mechanical hand too) I like everything fully optimized(perfect). I am a newbie but with the help of this guide I hope to optimize all by vehicles . But there is bit of a problem.

    The problem is that all my vehicle (Hero Honda Super Splendor, Kinetic Nova 135, LML Vespa Spl. [Self Start] ) does not have a tachometer.

    Please guide me to Connect a tachometer. (Which wire goes where).
    Going through their circuits I notices that with a bit difference all two wheeler work on the same principal [Magnet produces current –> CDI Unit —> HT Coil —-> Spark Plug etc. etc.)

    1. Now where do I connect the tachometer.
    2. Secondly When we say full revolution of any screw (as stated in this guide and all my Manuals)
    does it mean that starting from point A and after (un)screwing again reaching A (considering the two opposite points of a screwdriver as A and B) ?

    Thanks in advance.

  53. @Zmint..
    Yes you are correct for your query of A and B Points of Screw.
    As for Tachometer query,
    I guess you can connect it to the end of the Spark Plug Cable. Remove the rubber (which fits on the Spark Plug) from the Cable end. You can see the Open Wire. Here you can connect the Tachometer. Its difficult for me to explain here.

    Please email me the Photo of Left and Right Side View of the Carb of your Uni. at
    Then I may be able to tell you about the location of Screw looking at the Photos.

  54. Hello,

    Before coming across this article I tried tuning carb of Suzuki 150R and tunred the screw anitclock 2 revolution(a tuned engine just after 3 service with 5000 kms) But now im getting good milege, I would say double then usual but the pick has decreased a little. Is it ok If I countinue with this or will it effect my engine?

    Thanks for you kind reply.

  55. Hey, This is what i was searching for, Thanks for the info.
    Those baxxxxd mechanics don’t give any information when asked.

    I have avenger 180 and was suffering from sluggish performance, i tuned the fuel screw and now my bike sound well and accelerates well. Will try tuning both screws once i get hold of tachometer.

    Thanks again

    – Shashank

  56. I’m Unable to turn the air/fuel screw on my 2006 honda unicorn. Its tight and seems to be jammed. I took to a service center and they informed that the screw has a lock which has to be removed for it to turn freely. Please help me on how to adjust the Fuel/Air scree.

  57. Hi! Ashwini,

    I want to ask you two questions:
    1. I want to install K & N Air Filter in my HH Karizma R. The problem is I dont know what kind of mechanic can install it?
    I dont want my Karizma to be hurt/damaged.
    2. Will installing the Air Filter, affect my Karizma’s Milage?…right now its just above 43kmpl….I dont want it to be reduced. or should i wait for my Karizma to get old and then do such kind of mpdifications?

    hope you will help… 🙂

  58. I own Fazer. ODO: 1320KM / 3 Months

    Suddenly I noticed that the millage of my bike came down to 32-35, where till few days ago I was getting 44-48km/lt. And if I rev it after the speed of 70km/h the engine start to make huge noise 🙁
    (Though the respective RPM is normal with the speed, 70/6000RPM)

    Plz advice me what to do ???

  59. Hello Ashwini,

    Very nice article and it should be good for many people who are getting low mileage.

    I’m a HH Hunk owner and my bike is 1.5 years (7k km ) old and its very well maintained. From the beginning I didn’t let the service guy to tune the Carb i.c tune the air/fuel mixture to get a good mileage coz I think a company default carb setting only gives optimum performance and mileage. I stopped doing free servicing after 3rd and I’m doing my bike’s servicing by myself coz the service guy do nothing actually. My bike is giving 50-55kmpl in city ride. I frequently (1k-1.5k km) clean the Spark plug, as its good for mileage and performance. But still my stock plug has very less carbon deposit after 1k, very light black and the electrode is white like new after cleaning. My concern is it a sign of Leaner mixture?

    As you are expertise and its not related to this topics, still I’m asking.
    I use to drive in low RPM to get a good mileage i.e I shift up all gears at 2.5-3k RPM and 5th gear at 3k RPM (Single Ride). So is it good for the engine life? Or I need to shift up gears in more RPM? However my bike never ever hesitates to catch pickup in these conditions. Even in 3k RPM @ 5th gear it has a nice pickup and pulling power.

    Yet after 7k km I didn’t clean the Centrifugal Filter and Oil filter. Is it ok? or its ok to clean it after 10k-15k km?

    And its ok to drive @ 100+ km for long stretch during touring? I’ve experienced many people get changes in their valve clearance or engine noise, tappet noise after top speed drive. Massive heat can cause this.

  60. ^^^

    ur bike is running ok…..dont worry…..tune carb only when u are getting low mileage and cold start problems….

    and u can change gears at 3k rpm.

  61. Hi Ashwini, Your article is really excellent. Thank you very much for the guidance. I need some more info on this. I have TVS Fiero F2 bike which comes with Mikuni Carburator. I read you article and checked the carb and i only found single screw of bronze/golden color. I didnt find any other screw except that. I checked whole carb from 360 degree but couldnt find other screw.The idle adjustment screw is quiet visible and adjustable by fingers. So my question to you is, does this carb come with single air/fuel screw? If so, how to tune this carb for maximum fuel efficiency? I get mileage around 50kms which is dropped from 55-60kms after recent servicing in last month. Also bike gives misfires which sounds like Enfield exhaust(which i really hate. I want it to be smooth as Unicorn). I use IOC unleaded patrol. Now bike is giving black smoke which i think sign of something wrong in combustion chamber. Bike is purchased in 2005 with running 8900 only. Please advise. Thank you.

  62. Bit confusion to be cleared :


    I want to resolve a doubt regarding Carb tunning (4 stroke) with a tacho.

    When tuning the Carb (adjusting fuel screw), while keeping a eye on the tacho, I get a period of time (not point of time) where the tacho shows stable rpm.

    Ok it was bit hazy, let me explain it a bit further.

    The stage is set. Every thing is done, mean to say the engine warm and all that.
    I close the fuel screw fully, the rpm is at lowest say 1000, now I start opening the screw,
    the rpm start to rise (not fluctuating), very slowly I am opening the screw, the rpm are rising, still opening very slowly, still rpm rising….., and then comes a point (say point A) when the rpm stop to rise(or decline) say rpm 1700. I continue to open the screw further, rpm still 1700, opened the screw, still rpm 1700… And finally reaching a certain point (say point B) the rpm start to decline. Now we have got a period of time (from point A to point B [1¼ to 1½ open screw) where the rpm are constant. No where do set it for optimal milage.
    While tuning a Carb with a tacho, actually what are we trying to attain is Highest CONSTANT RPM (not Highest RPM) ????

    Also while inspecting the Spark plug. I have a bit of doubt. When we stop the bike it is mostly running at idle. Will inspecting the Spark plug after it has run on idle for sometime. give the true picture ? I think switching off the engine instantly, when its running in its economy zone and then inspecting the spark plug, will give a better idea about the combustion Or am I, unnecessarily taking it a bit more seriously.

    What is your idea ?



  63. Hi Ashwin..

    Glad to see all the post, mainly you Article but I’m yet to try. However I just a few question and requesting to help me please….
    My bike
    Pulsar 180 UG3(digital)

    Modification done just a week back:
    Twin Lead Spark Plugs
    K&N RC1060 Air filter

    I use to mileage around 40-43 in city limits. however about a month ago its giving 35/L NOTE: this was before upgrading filter and S-Plugs. And even after installing above i’m getting the same mileage, my notification is this is happening after the last service, though mechanic is good at service but not that technical he is.

    So, the conclusion is shall I try ur steps and check if I get a good mileage and also can you please let me abt twin lead spark plugs? is that good? will that hurt bike anyways? please help Ashwin, any advise would be greatly helpful and appreciated. Thanks a lot… waiting for your post…

  64. I own a bullet. I like to know if it is the same procedure for tuning the carburettor of bullet.otherwise please explain the procedure for tuning the carburetor of a bullet.

  65. I own 95 Model Royal Enfield with stock carburetor. How can i tune the carburetor for mileage.Is it the same procedure explained above.I am a little confused about tthe turining of the air-fuel screw.

  66. Hi Ashwini,
    i was expecting somebod to write this kind of helpful things on our owned bikes , this is a good thing that now we can take care of our bikes ourselves , thanks again.

  67. @ Zmint ……

    Inspecting Spark plug..
    If we see a dark black color on the electrode of the spark plug!! that means its tuned to Rich(Consuming more Fuel).
    If we see the same in a light Grey or Grey that mean its tuned to lean(consuming more AIR.
    When you see the Spark Plug Electrode with BROWN in color that is the proper tuning, in-dead proper mixture of air and fuel..

    What say Ashwin??

    Ashwin, I’m still waiting for your response on my first post.. please help. anybody please….

  68. this is really good but i havea honda aviator which is a nongear 4 stroke bike i had done some porting and stuf it did nt work out so i purchased a new engine but i still wish to get a better performance i go for long ride but i still dont mind less average i just want better performance

  69. he well this is truely stated practical output delivering steps towards d avg of d bike, coz i had tried these steps myself on my p150 dtsi, an that time i was not even aware of this article, but reading it today it this person has just delivered d tips which i follow along wid my frnz……. so this tips really work. VERY GOOD JOB MAN.

    4 days before i hav cleaned my carborator an has set d fuel screw at 5.5 rotations anticlockwise frm full lean, this means my setting is more towrds a richer side, an earlier also i use hav this setting for a good pickup an avg combnation, but since this done now, my rpm which is at 1.1k, in d idle mode it goes down an bike shuts off. an also sometimes my rpm rises in idle mode upto 3k an an slowly drops back to normal. whts d problem ?

    2ndly since last 1month my bike is having starting probs if its kept idle over 1 day, an am abt to change my plugs coz they r now 15k km old, thinking that changing plug wud solve my probs, an i wud b using d new bosch 2 head plugs. tellme if this d solution for starting probs ??

    and i had properly cleaned my carborator 4 days ago along wid d plugs, an as u said d plug color i checked after 1 day of cleaning is black (not complete dark black).
    and since one last one year i been setting d fuel screw myself an i hav idea abt how much avg i get for my bike as per d rotations i set towards richer side, so no problem wid avg.

    can u add some solution to d 2 of my above problems.

  70. Aditya,

    I’ve set the Air/Fuel gauge to 3.5 rotation, which is not completely into lean, but yes it is lean.

    Idle and cold start is fine on the bike, i have P180 UG3.

    As you said, you’re getting avrg… how much are you getting???

    So far, i’m struggling with 35km/l with the above tuning, though I too have installed twin head spark plugs(Bosch)

    • Dear Brothers,
      In the above article as it is written that all 4 strokes engine have fuel screw is not correct .Most of the 100/125 CC,4 strke bikes in india are having air screw .
      Bajaj pulsar most of the models having CV carburetor having fuel screw ,its stock setting is 3 to 3.5 anticlock turn from screw close position. you will get good milage at 3.25 turn .but dont get greeded by milage as if your bike running lean for long run your bike piston ,rings and valves get wear out quickly .So at the cost of milage in short run you have to pay 5k to 10 k maintenance cost which is not advicable.

  71. @ shinde:

    1stly i an abt to try d twin plugs, but heard that it will just slightly giv u little bost in avg but not much.

    2ndly in my setting of 5.5 rotation i get a avg of 50+ even if i ride my bike between 80 – 100kmpr speed, an if i ride it between 40-60kmphr i get 55+ avg. But that total depends on how v pull d throtle. When my frnz ride my bike in 5.5 current setting my avg drops to 45 an below depending on d way they drag. When i ride my bike i get good avg coz i follow certains points-
    >> changing frm 1-5th gear i dont drag my bike i.e i dont open my throtle above 3k rpm, my gear shifting is done around 2.5k rpm, an once i get in 5th gear then i start pulling d throtle an that too not in much harsh way. so on d 1st 4 gears i dont race d bike above 3k rpm. thats y i get so much difference in d avg on my bike wid me an my frnd riding it.

    u said u get 35km/l at 3.5 setting, so u try riding ur bike between 40-60kmpr coz ur setting is set to a lean type, an if u drag ur bike anytime do it in 5th gear, u wud then get d result in ur avg. Coz ur setting is towrds lean then its meant to ride constanlty at a low speed, if u speedup in this setting u may feel some load while u getting to 80 or 100 speed.

    when i had d 3.5 setting an i was riding my bike around 40-60kmphr i was getting a avg of 60+, but if i tried to speedup around 80 to 100kmphr my avg use to go below 50, an around 100kmphr i was feeling load in my bike while running an it was also taking much time for my bike to reach 100. thats y now i changed my setting to 5.5 – so now i touch 80kmphr in much less time an the bike feels free when running on 100kmphr.

    if ur most riding is at d speed of 80-100 u can try 5 rotations, if u keeping it towards lean then try not speeding up much or else it means u r nor riding in d manner for which ur setting is meant for.

    an when i check my avg i mostly do it by just filling 50rs petrol to get more accurate result.

  72. As Aditya said, the same method of gear changing I use and my Hunk gives 55kmpl. If you are riding alone then 2.5 to 3k RPM is ok to change between gears but you have to quickly shift to upper gear without letting the bike slow. If you change from 2nd gear at 3k RPM that means the 3rd gear will start pulling from 2.5k RPM. The time during the gear change the RPM goes down and raise again so if the RPM goes too low that will put pressure on the engine. Also you have to release the throttle at that time. And it’s a fact that driving at low rpm damages the engine even. I did that before but now I realize that its not good for the engine to put too much load. Like don’t drive in 5th gear at 2.5k RPM. I basically now change gears 2-3 @ 2.5k RPM, 3-4 @ 3k RPM and 4-5 @ 3.5k RPM. But RPM-Gear method must be depend on the weight that engine carrying. If you r riding with a pillion a little more RPM will be good for the engine.

  73. yes this guide is for bullet also….and i thank u all for the comments and i thank bikeadvice which allowed me to come up with the article….truly, bikeadvice is best bike website.

  74. Aditya,

    well, I use to race the same earlier n I use to get minimum of 40km/l… but i don know wats wrong now… I have made little more changes, and I’ll get back in a day or two with the results…..

    Any other suggestion of interesting discussion you have ? please share… its for everybody..

  75. shinde u can post ur results as u get them.

    has any one idea abt cold starting probs.
    i hav to use 4-5 kick attempts to start my bike if its not used even for a day.
    the probs may b among d following:
    1. carburator
    2. choke
    3. idle rpm
    4. spark plug

    one week ago i hav sreviced my carb. along wid a proper tuning much to a richer side. so may b dats not d probs for me

    my choke is working fine

    my idel rpm is 1.2k, so its proper i guess.

    my spark plugs r 15k km old an now am thinking of going for 2 head bosch plugs costing 110 rs each, so i think my cold start probs lies in my plug. do u think its rite guess ??
    am surely gonna change d plug even if it wont solve my prob coz they r very old now, but wanna kno my exact problem for d cold start, i guess it shud get solved after changing plugs.

  76. Well, u can give it a try, couple of weeks back i changed both the plugs to Bosch Twin Electrode spark plugs. its fine, u get soothing power… u should really concentrate on the knocking noise to check the effect

  77. Hi Ashwiniy I’ve a HH hunk and I want to know the exact location of the carb’s fuel mixture screw. At the left side of the bike if I look angle wise just bellow the fuel on/off knob there have a golden/bronze color screw in the carb closest to the engine. Is it the fuel mixture screw? I prefer to show you a picture, but right now I don’t have any one. I guessed that screw. And yesterday I noticed there have a slight vertical dash ( | )mark on the screw circle area at the carb. Is there have any marks for the Idle mixture?

    I’ve attached an image in the bellow link. Please take a look.

  78. Hi Ashwini,

    Thanks a lot for this carb tuning guide.I followed this and have found startling result with my Suzuki Zeus which is a 125cc.But I seemed to stoop upon a small issue.

    Before I cam across your tuning guide,my Zeus which is a Mikuni VM18 carbed 125cc, used to have hiccups when the throttle was suddenly twisted for streaming acceleration and my bike used to idle around 1000 to 1200 rpm.I used to be left behind when there was case of opening throttle on highways.Disappointed then,I followed your guide very stringently and at normal engine temperature (after a ride of 5-6 kms and 15 mins approx).I increased the RPM to a steady 3000…….then I made the fuel mix leaner,here just before a quarter to fuel screw lock up(leanest), my engine stalled,I then had to increase the idling to 1500 to bring the engine back to life.After that I went into the leanest screw lockup,engine rpm around 1200 unstable.Then I started increasing the fuel mix to rich,I used to do one rotation and let the engine settle, the rpms were not stable kept climbing and droping +-200rpms.Then finally after 4 screws anticlockwise, the rpm stablised and constant at 2500 rpm.But 2500 rpm for my bike is way above normal idling speed,so this time I decreased the rpms through the idling screw to 1600rpm, below 1500 rpm the idle is not constant and below 1300 rpm,engine stalls.Then I took the bike out for a ride……….the acceleration this time was intense,throttle response crisp and no hiccups and the most amazing thing was I felt power all the way upto the rev range……….the bike also felt too quick!!!! Then as I slowed down and came to a stand still at my home……I found that idling speed was now around 1800 rpm,while I had set it around 1600rpm at standstill.Assuming that due to intense acceleration and throttle response,engine was warmer which made the idling go up,I decreased the idling to 1500 rpm, which if warmer would only climb to 1700 rpm.The engine rpm is constant at 1500rpm and is irregular below it.
    So i assume that the idling of my bike is 1500 rpm optimal.

    But now my question is that,in the owners manual,it is advised to keep my idling rpm in the range of 1400-1600.My bike is 1500 rpm at normal standstill ideal and rises to 1700 rpm after speeding and accelerating for sometime.So did I do everything ok???? or did I screwed small time??

    Also my mileage used to be in excess of 70kmpl…….I would be satisfied if it gives around 60kmpl now along with the added performance……………….does my present idling and carburettor setting compliments this????

    Last but not the least a lot of heart felt thanks for such a good guide.I am really satisfied with the results,I just need to clear my doubts and hope that you would help it 🙂 Thank you again.

  79. Hi Aswini ,
    I own a hero honda splendo plus + 2005 model , and recently i had a feeling that my Service centre was not paying attention to the actual service but just taking a way out just to make sure that the bike atleast works as what it is doing , i mean the attitude of chalta hai and aise hi chalega, so lost some faith in them , i was searchig for some thing which will make me work with my bike so that i know it better than any body else . after i worked on my bike as you have suggested , i would like you to comment on what i have obeserved so i know i m doing any wrong .
    this is what i have done ,
    1) removed the spark plug
    observation :
    1)black carbon powder on sides of electrodes and on the electrode
    2)the center electrode 2mm above the ceramic insulation and the other electrode bent over giving a gap of almost 1mm.
    so i cleaned the spark plug and maintained a gap of aroung a saw blade should be fairly aroun 0.05-0.08 mm as described inthe manual

    secondly during cleaning of the carburator , after removing th carb fromthe airfilter tube observed minute particles int eh tube so assumend that the filter was not regularly cleaned at the service centre so cleaned it again as per instructions int he manulal. also noticed the air suction valve , do we need to clean them let me know how to do it ,

    ok commingt to my observation on carburator tuning , after removing the carb i observed another screw on the other side of the fuel screw and knowing i didnt have to clean it i cleaned it any ways so i suppose i will have to work little more on tuning on my bike , so i started the bike since i do nto have a tachometer just felt the vibrations and the noise ,
    observed that when the other screw is also tuned it affects the speed at thich the noise varies so assumed that should be directly connected to the RPM .
    so after tuning both screws so that i get neither too fast not too slow speed or noise and smooth vibrations i have set the bike , this i did yesterday ,
    and after doing this if found the bike pick up was fabulous when throttle was oppened which i didnt felt for so many days for now ,now at low seed the feel is that the engine is not getting enough fuel to support the power required at lower speed , so what should i do , i know you will ask to do the tuning afgain , but since i do not have RPM meter i have no options but to feel the bike and get it done i dont knowhow much time it is going to take further but would apprecialte if you can guide.

  80. amol, if ur bike doesnt have tachometer then u can rely on the color of spark plug after tuning. the color shud be choclate brown.

    soumen, yes this is the screw which is bronze, for air fuel mixture there is only one screw.

    Suddhatma Mukherjee, thanks for the compliments, u did all correct, and higher idling wont do any damages but u can reduce it to company specification.

  81. Ashwini, thanks for your confirmation that the job is correct,my bike doesnt heats up excessively anymore,another development from running a too lean mixture condition.I need another advice,It was easy spotting the Fuel Screw as it was a Mikuni,but what about a Keihen CV carb,where is its fuel screw??
    They have something they call it Idle mixture screw…….is it the Fuel screw??? where is it located??

    After riding my bike with such good carb setting my Elder bro also wants me to tune his ride,but the only hitch is that his make is Keihen CV carb………so needs some advice about the location of the screws …. Thank you again 🙂

  82. Suddhatma Mukherjee,

    according to my experience every carburettor has a bronze screw/golden color scre which is know as air/fuel screw and it is common in all type of carbs. so it wont be diffcult to find out.

    but if ur not sure then u can ask any mechanic and he will tell u the correct position.

  83. Hi Ashwini /Sudd
    just for my knowledge on the other side of Keihen CV carb what is the purpose of the screw which is placed at an angle 60deg to horiozontal this screw i snormally hidden under the tool box of splendor plus bike, just for inforation , ans definately this has to do some thing with the idling ,so would appreciate if you can help on this .

  84. @AMOL

    Been there done that,my brother’s Wind125 now hums perfectly.So I have done the Keihen CV Carb.Yes the Fuel screw is located on an odd spot for Keihen Carbs.Its inwards and opposite to the vertically placed Idling screw.

    For the Wind 125,the carb is on the right side,The Idling screw is vertical,pin head touches the throttle cable,nail head is downwards.Located opposite to this position on the inner side of the bike,is the bronze colored fuel screw.Reaching this spot is a trouble,no light reaches there, n u need some1 wid a torch.Its is horizontally placed.Hope now you can find out what it is under the tool box of Splendour,a fuel screw would always have a Gold or brown color as Ashwini suggested.

  85. Hello guys,

    I’m just coming back to inform about my current experience, I tuned my bike nearly to 3.5 rotation (air/fuel screw), now i got proper tune… I have to rate then, Power is 8/10 and Mileage is 10/10. NO hiccups, No misfire, and goes smooth. On this tune, I can reach up to 122km/h (MAX) and while on city limits i’m getting 45 to 48km/h mileage… Again!!! I got K&N intake installed as well… Thanks Ashwin:)…

    It just needs hands ON…Keep trying but not screw up somthing. Just try what Ashwin said, and you are there!!!!

  86. I have a Hero Honda CBZ classic with TPFC. I am only getting a mileage around 30-32kmpl.Is there any way i could get more mileage out of my bike ! How can i possibly tune the carburetor of my bike to get good mileage,..Will changing the carb help ? Somebody please help on the matter

  87. @Hashim……..

    30-32 kmpl for classic CBZ in 2010 is ok,CBZ was always known for its thirsty but power happy nature.But if u need mileage and not power which is the natural trait of the bike ,u need to run a bit leaner mixture also check out if the setting is optimal,because on optimal settings CBZ used to stretch the mileage around 40kmpl max.Pls dont go for the carb change,u will waste the bike’s originality.However if you really want to cahnge it,go for the New Hero Honda Acheivers Carb.Thats all I can say.But pls dont go for Splendour or Discover’s carb,engine would seize sooner,for this old bike.


  88. how can i tune the carb of my CBZ classic to a leaner mixture,..can i change the jet size of the carb for better mileage…i need a mileage of 40+ for the bike. i had installed a wider stud type rear tyre.will it affect mileage a lot

  89. @Hashim, the wider rear tyre is definitely failing your mileage.Your bikes optimal setting is lost.To rise your mileage you can either change back to the original set or tune your carb to leaner mixture.A Classic HH CBZ wont give you above 40kmpl at the best,if you change to the original you will get it.Lowering carb jetsize is not recommended,too Lean mixture would fry the valve trains,which again wud lead to engine loss.
    What you can do is follow Ashwinis guide for the optimal settings of the carb.This setting would give you the best settings of mileage for your bike.Leaner mixtures than the optimal settings of your bike would heat your engine up,lowering its life.

    So,for getting a bit more mileage from your bike:
    1.Change rear tyre to stock(original),fatter/wider rear drains mileage highly.
    2.Follow Ashwinis guide above and tune your carburetor by the fuel screw to get its optimal settings.

    These two things would change your bikes mileage to 42kmpl to the best.Its a CBZ afterall,powerful 1st 150cc,dont compare it with any other newer 150cc bikes.They are not CBZs.

  90. @ hashim, bad mileage is not only a result of a badly tuned carburettor but bcoz of a worn out engine also so pls see the bike to an svc so that he can check the condition of the engine.

  91. vaisagh,

    to increase the top end the carb tuning shud be on a bit of leaner side, but it is not for the engine in later run.

    so u shud settle for the idle mixture.

  92. first of all these are very useful tips

    i got only one question….

    is this true that BOSCH Super: twin electrode Spark Plug will increases milage my pulser 150(digital)

  93. dude prasad_knight –

    i hav a p150 dtsi 2005 model, i purchased bosch twin electrode spark plug for my bike, 110 rs each.

    after putting it my bike got very good at idealing, i could feel d power when i race d throtle, it felt as if bike got more smooder, an my avg increased just around 5km more, but only for 2 avg readings of mine, an now its like my bike giving normal avg which i used to get before the bosch plugs.

    but if u r abt to change ur plugs then go for twin electrode u can feel nice response frm ur bike an they wud last more longer than normal single electrode plugs.

    if u can afford for more money, the go for NGK iridium plugs they cost around 550rs each- they will giv u more avg an more power as compared with bosch.

  94. Hi,
    I own a CBZ xtreme. My boy gets heated even after driving a very few kms. The noise of his engine gets harder. Also the mileage is as low as 30 kmpl. I use ELF moto gold as engine oil. I am clear that the problem is with the carburetor but I do not know how to adjust it for better performance. I am not worried about the mileage, rather I need a noiseless smoother engine without raise in RPM after some kms.

    Also let me know whether replacing a K&N filter would give me a better performance with a smoother engine.

    thank you..

  95. hello ashwini,
    actually i hav a hero honda hunk, its a 2008 feb model,,,
    intially i tried to tune my bike for a good mileage, by adjusting this air/fuel mixture screw, but i ended up with a total mess, my bike started to stall, in between anywhere….
    after that the service guy corrected it, so that it never stalled again as before,, but according to me the performance which i m getting is not optimum, i thnk that m not getting the good throttle response, and the bike is sometime very good and delivers nice ride, but maximum times at around 60 kmph i feel that the engine is hard and struggling,, so what do u suggest should i try to tune my bike again???

  96. hi ashwini,
    can u tell me that about how many revolutions are optimum for air screw of the carb.. ihav the hunk 2008 model,and its carb is keihin make,,,and wht is the maximum mileage that i can get from my bike(hunk),,,
    thanks in advance

  97. i want to tell that im getting a mileage of 40 kmpl and my air screw of carb is set at 1 full rotation,, and i drive anywhere without any restriction of speed…..

  98. My yamaha fz 16 has done around 4700km and am interested in tuning the bike toward a bit more efficieny. I would prefer to do it myself rather than trust the useless SVC guys. Will there be any long lasting effect if the bike is tuned before the 7500km running in period?

  99. hey vineeth,, according to me if u hav done 4700 kms on ur bike,, then there is no problem in tuning ur bike ,, but one should tune the carb only when its not providing optimum mileage, or pickup,, so if ur bike is giving u 40 to 45 kmpl then dont change ur original factory set carb tuning,,,,, but if u really want to do that,, then u will hav to do it through air mixture screw.

  100. i suggest that u tune ur bike only when necessary, or if it has been messed up by svc ppl, or ur not getting gud milaege, performance, poor starting etc.

    tuning it otherwise will create problems for begginers

  101. Want to know – whether it is possible to fit 140/70 17″ rear tubeless typre to Pulsar 220 DTSi without doing any modification? (stock one is 120/80 17″)

    Is there any possibility of upjetting to 32″ ULCD carburetor? if yes, whre I will get it done in Pune.

  102. plz help to find air/fuel mixture screw in honda shine. is tachometer really necessary to tune? if yes how and where to put the tachometer? also if u give ur email id or phone no. it will be very usefull to me…

  103. I have question/concern. I just went out and checked my bike, I see my carbs. (two of them)

    I am looking on the side with the fuel cock and I see two set screws on both carbs. How do I know which is which, they are both the same type of screw, (none are bronze) one sits out a little further away from the engine than the other

  104. they appear to be drains when i loosen the screws fuel drips out of an opening on the bottom.

    the bike is a yamaha vstar custom 650cc

  105. “As you make the mixture leaner, slowly the engine RPM decreases… Go on doing this until you have put the fuel screw to the leanest possible point. At the same time, ensure that the engine does not stall, by turning the idle-screw.”

    Pls what do you mean by saying at the same time, ensure that the engine does not stall, by turning the idle-screw.”

    Engine will surely stop at some poing when the idle-screw is turned then how do you say that first turn the idle-screw to set at 3k rpm and then again turn the fuel screw to the leanest posiiton ans so that rpm decreases and again why are you saying to turn the idle-screw.

    I don’t understand pls explain?

  106. hi Ashwini,

    i have a mileage problem with my Pulsar 200 its one and half year old, it used go give me a good mileage of 52-54 in city conditions. i used to travel for my office daily 60 KM’s (upwards and downwards). recently i observed that there was a drop in the pickup and i went to service station. they changed the Clutch plates and said it will be fine now. i got back the pick of my bike, but the mileage was dropped drastically, it is giving me 41KMPL now. even i tried to tune the carb as per your doc still it is giving me the same. i have one more doubt when i am driving i sensed some sort of tik-tik sound coming from the chain. service people said need to replace the Sproket. does the chain sproket will play a role in the mileage. but my wheel rotates freely without any lagging.

    please suggest me what to do.

    M.Surendra Kumar

  107. Surendra,

    Hi, just thought of giving you some info. Well you are getting 41kmpl which is a good mileage when it come to talk about Pulsar 200. Just do the proper and perfect Air/Fuel mixture according to Ashwin’s post and you would have a healthy Engine. As said before P-200 40kmpl is the best average.
    The knocking noise should be either from chain or may be from engine, just double check and confirm. If it was from the engine you might have to adjust the engine timing chain, but if its from the chain which needs replacement of sprocket then take it a mechanic to get it changed. However just the noise would not affect the average for your bike, I hope the chain is not jumping teeth of sprocket.


  108. hi Shinde,

    thanks for your comment, yesterday i went through the tuning part as per the Ashwini’s procedure. now the bike is doing good. as of now i didnt check the mileage.
    but iam sure the knocking noice is from the Chain. also observed that when iam taking the bike in reverse the wheel rotation is not smooth.

    anyway now i will check and let you know the mileage how much iam getting.


  109. Hi Ashwini

    Is it o.k. with giving chock for oil to spread well within engine and warm-up instead of riding the bike before tuning?
    Because sometimes we use chock for starting trouble in winter season..

    Thank You.

  110. hi ashwini….
    ur article is awsum…
    i tried it on my pulsar 220 dtsi….as it has a fuel screw…
    so if i messed up and do a wrong tuneing…..will it effct on ma engine?
    or i can tune as many times as i want???

  111. Hi Ashvini,

    I tried to tune the carb of my Apache RTR but the feul screw is very tight. it is not moving easily and even not coming out fully. As it’s of bronze material it’s head will damage if i press more.

    Please advise


  112. Hi Ashvini
    very useful topic…
    do u please tell me that for bajaj discover 135 dtsi the fuel air scrue should be rotate in which direction imean clockwise or anticlockwise???
    ihave to increase the pick up and power with compromise a little bit with d mileage….

  113. actually when i am rotating anticlockwise den after some times the rpm decreases!!!!(it should be increase as i am opening the scrue means more fuel flow)why ???

  114. Hi ashvini

    Thanks for this article.

    I have some doubt.I was bought a HH super splendor on 2006.This year(jan 2010) i done my 5 th service at one service staion,where i serviced earlier.After that petrol is leaking from the carburetor. I dont know reason. Again last month i done my 6 th service at the same service station they cleaned the carb. But Again the petrol is leaking from it and also the sound of the vehicle is changed. While i asking they cannt tell the proper reason.I just want to know the reason.

    ( Note : before my 5 th service the vehicle is in off mode for 15 month.Nobody drive the vehicle at that time. May be this affect the performance of the bike.Please clear this)

  115. thanks all for your compliments…sorry for late reply as i was out of station.
    @ balraj if ur carb is leaking then you shud immediately check with some qualified mechanic. and is your carb overflowing???

    @ anirban the rpm is decreasing coz you are putting too much fuel in the engine.

    @gopi seems the screw has stuck in carb, pls see a mechanic.

    @ saroj yes you can, no probs at all.

    @all see link – for tuning related to fi bikes

    @ maitrey you can try as many times as you want as it is trial and hit method.

  116. hi, Ashwini. I ride a 1985 Yamaha virago, 1100. and i’am trying to tune my carbs, they are hitachi,on a v-twin. the front plug is a always full of black carbon more so then the rear.I have the idel screws, the fuel screw, and i have a screw between the carbs,iI think this the syncronising screw. Do I use the same method to tune these carbs? thankyou , your advise will be greatly appreciated. Thankyou Brian O’Brien

  117. Hi Ashwini,

    Im so happy tht i got some1 like u to get help from for fixing one of my issue with idle rpm of my bike. I hav got XCD 135 and one of my frd mis-tuned my bike by turning Air screw. As a result my engine`s idle rpm dropped. Since then my bike is not giving good mileage,pickup and engine gets off whn i stops at signal or when i press the clutch. Now even the service center guys r not able to tune back to previous settings.Im so disappointed with this.
    I read ur article above and understood the concept and feeling like to do it myself. Can you pls help to let me know the step by step process to fix this issue.I need to set my engine at 1400 RPM steadily with correct process. PLsssss Help Ashwin..i wud be so thankful. Javed

  118. Hi ashwini. I hav pulsar 150, 2009 one. Can u pls tell me where is the fuel screw. I saw a golden color screw near the idling screw. But i am not sure. The pipe like assembly is carb right. In that a golden color screw is placed horizontally. Can u pls post of a photo of carb n fuel screw.. And my engine sound is not lik other pulsars.. It misses the bass or grunt and sounds somethin like platina.. What could be the reason? If i adjust the mixture wil i get the original grunt of my bike? Pls throw some light on this.. Waitin for ur reply..

  119. @ maitrey yes this process is for 220 also, infact it is for every bike.

    @javed, kindly go thru the article thoroughly and tune the bike in described way.

    @prabhu the fuel screw is there at the left side of carb , color,

  120. I did this tunin on my pulsar 150. I could not find noticeable difference in performance. Totally frm full lean mixture it came 7 turns anti clock wise. Is it rich or lean mixture? I want to get little more performance without affecting decent mileage. How many turns it should be frm lean mixture?

  121. Hey thnks ashwini !
    But 2day i hav put the fuel screw to leanest nd the bike is working f9!
    Will it decrese my fzs mileage or hav any other affect?

  122. Hi every one I have a 2005 model bajaj discover dtsi 125cc. I get low millage 35km in city and 42 at highway. mechanic say that the mixture screw is faulty i try to buy new mixture screw but I its not available in market. my bike give black smoke, pls help me to solve my problem

  123. Hi Ashwin,

    Just wanted to know the specific reason for setting the RPM to 3000 while tuning the carburator as per ur instructions..!! and then making the tuning to 1000 RPM after making it to optimal setting..!!

  124. @Mr.ashwini kumar
    I own apache 180 and it is brand new.When i rise the throttle,engine rpm halts at higher range for some time and then comes down.Is it due to bad tuning or is it due to clutch slippage.Please answer me as soon as possible.

  125. @ Ashwini..

    i followed the method as my pulsar 150 UG 4.5 had a bit less pick up than my friend’s p150. after the process explained by u. pick up is absolutely fine. but i dropped tremdously on mileage… pls help me..

  126. Ashwini bhai i have a pulsar 180 which has a UCD 29 carburetor. I am confused regarding the screws. Main yeh nai samajh pa raha ki air aur fuel screw ek hi hota hai ya alag alag. Please get a picture of the carb and highlight that where is the air screw and where is the fuel screw. Please send that pic and reply to me on I would be very greatful to you.

  127. My Bajaj Boxer is getting very low milage.I don’t know whether the adjusting brass screw is a fuelsrew or an airscrew ?The carburator is keihin.Please give a reply.

  128. Hey laxmikanth, P 150 UG4.5 performance is really better than UG4 or both rides r same?? What abt refinement.. Any diff man? I think both performs in same manner in road. Any increase in pick up or top speed? Let me know this…
    I too tuned my carb n resulted in low mileage. After tryin More than 5 times now i settled wit the lean mixture. Hav to do it very patiently.

  129. i got a big doubt whether wat bike to options are apache rtr160 and fzs..i need good mileage with good cousin says go for fzs..but i heard a lot of complaint about fzs about its poor cousin said tuning the carb will yield good mileage around 70+ if driven around 45kmph..wen i read your article many people commented saying hiccups..which bike can i go for???pls let me know within two days

  130. hi,
    I own a Bajaj Boxer. I do not have a Tachometer but I tried tuning it as us mentioned earlier hearing the sound. I increased the RPM using the Idle screw ans then turned the Fuel screw/ bronze screw (clockwise) turned fully clockwise till the point it cannot be turned further and found that the RPM increases further at this point. Should I keep the fuel screw in this position as the mixture is the leanest at this point and reduce the idling t get maximum mileage.


  131. Where is air/furel screw i passion pro bike i have this bike model 2010 i have starting problem in morning and i get the average of 45-48km/ltr
    can you help me i have said to service centre but no use

  132. @deepak
    fuel screw for any herohonda bike can be only seen if u open the tools box.Inside the tools box a hole is provided which is directly above the fuel screw.Since its a new bike,tune it only after 1000km.

  133. Dear Ashwini,
    Thanks very much for your wonderful write-up. I live in Bangladesh and have had (still do) a two-stroke Japanese Honda H100S CDI bike for 17 years. I now have a Hero Honda CBZ which I have already ridden for 8000 kms. I’m a DIY kind of guy and have found your article very useful indeed. Keep up the good work. Cheers!

  134. Hi Ashwin,
    I tried to tune my Bajaj XCD135 with the procedure mentioned by you and didn`t found my engine/carbeurator responding in the way u mentioned in ur process. I can see my bike`s engine slowing down when i turn it in full clock wise(lean mixture) but didn`t found again slowing down when i turn it anticlock wise(Rich mixture). Infact my engine just become harsh when i turn it more and more richer. So i m not able to find the threshold point where my engine give max RPM and balanced mixture. Would be very grateful if u can pls help. Thnx.

  135. Hi guys
    iam going to buy a new apache rtr 180 next week
    before buying it , i have a doubt about mileage , the tvs mechanic said its gives 45 kmpl on smooth drive , i need a minimum mileage of 40kmpl . the bike should not go below 40kmpl, and can any one advice me on this .

  136. I have Bajaj Discover 110 CC, Iam getting only 40 kmpl of mileage, I have given for full service but still not succeeded, even i have changed new Clutch as per service person’s instruction, but no use, previously I was getting 60 kmpl, but for past 8 months Iam struggling to get better mileage, my bike doesn’t have Tachometer to check RPM, how can I tune my bike, pls get me out of this problem.

    • just change drain pipe of your bike, let you know
      the pipe fitted between air filter and carborator it comes in many shapes
      1 straight pipe
      2 knot pipe
      3 wave shaped pipe
      4 funnel shaped pipe
      these are pipes you want instal in your bike
      i to have 7 years old bike wind125 and it gives top speed of 130-140 km/h 65 km/litre of mileage so i am satified about my bike
      KNOT SHAPED PIPE is best for bike under 150cc

  137. I got the new unicorn dazzler . Now i am having vibration problem above 50 , so i accidentally messed up by turning my ideal rpm screw . Then i found my millage was only 45 kms , with 1500 ideal rpm . Now i have reduced the idle rpm to 1000 rpm , will it affect my engine performance ?

    Note : I have not messed up with my air fuel mixture . Please clarify me

  138. dear friends,as a lay man we normally tighten fuel screw full and withdraw two and half turns/two and quarter turns.idle screw to our comfort.l tell me howmany turns i ‘d withdraw after fully tighetening.all this am short of tacho help

  139. Hi Deepak Raj,

    I have Discover DTSi 100 CC purchased 2nd hand at price of Rs 35000. One year old and 10000 Kms run till now. As soon as i purchased it I tried to check the mileage It gave 80 kmm/per litre. And the bike at 5 gear was running so smooth that I enjoyed very much. Very less noise engine was so silent that I cant believe its performace.

    Then I put the bike for oil change and servicing. After that I am noticing that engine get heated up more, even on small journey in city for 4-5 kms. Also I am not enjoying the ride at 5 gear, its not that smooth any more. engine is making more noise. I cannot confirm whats the problem is. Also it seems like he has done something with Tuning or fuel/air screw.

    Please help me getting the old tunning of Bike back.

  140. dear ashvin,
    i have super splendor.i do not have tachometer to attempt tuning as defined by you and most request is i close fuel screw to maximum and withdraw same by three turns anti i messing up your guidence ?or must i buy tachometer.milege is mere 28 km/l on my bike.please help if it permits you alternatively i’ll go to authorised center and insist to do tuning as optimised by you.great effort and best regards/gouraiahashili

  141. Hi Ashwini,
    A great article on carb tuning. I have a Hero Honda “Street” auto cluth bike and using it for 13 yrs. No problems till now but of late the bike stalls and stops when driving on high gear and when I brake at a signal or a speed braker. It fails to start then. Starts after waiting for 5-10 min. What could be the prob. The local guys are unable to fix. Can you help.

  142. Hi Ashwini,
    In my previous comment I forgor to mention that I could locate only the Idling screw and fuel screw which is to the left of idle screw but no air intake screw. Whee is ti located?

  143. I am doing my 4th yr mechanical engineering and i really dig bikes!! i am really awe inspired by the technical knowledge you possess and the clear guidance you have provided!! how is it that you have acquired such an in depth knowledge??

  144. HI Ashwini,

    Firstly, thanks for the input.
    I own a HH Splendor 2003 model. Plz help me find the Air & Fuel screw & Idle screw on my bike.

    TQ in advance.

  145. Hi, Please help..I have pulsar 150….when I drive my bike after the engine gets cool than there is some sound comes from silencer like *small blast* and as soon as engine gets warm this sound stops…..PLZ tell whether it is a problem or not..

    I have it serviced from bajaj workshop and tunned my carburator as per your article but it does’nt work for my bike. It has completed 11000 kms.

    Plz reply …!!

    • Hi! Ankit,
      you’ve tune ur carburetor to the leanest side. i’m sure when you slow down after going few k.m. , there will be a small blast like sound from ur silencer and also ur acceleration will not be smooth, it would be little hard.

      so 1st make sure there is no problem in ur silencer, secondly make sure ur air filter is thoroughly cleaned before tunning ur carburetor.

  146. I own Yamaha YBX 2001 Model for past few days my bike is creating problem actually I am in Goa due to moisture silencer of my bike has some holes I patched them with MSeal I also replaced the air filter…
    initially the spark plug used to be wet with carbon not wetness is gone but lot of carbon everyday..
    what should be the problem when i replaced the engine oil it turned black same day..
    is there any problem with the engine or replacing silencer will help?

  147. i own a 8 year hero honda splendor. and now decided to modify it to get max. performance from it.wat kind of tuning should i do to get the max. performance, may be not concerned about the fuel efficiency of bike to much concern

  148. I tried tuning according to the process mentioned above , I tightened the screw and made the mixture leaner , then slowly tried to make the mixture richer , but it hardly matters. Even if the screw is removed the RPM remains constant @ 3000 RPM.
    ie: Nothing affects the RPM whichever way the screw is turned , even if i remove the screw.

  149. Hi, I have a question.
    I have a Honda two-stroke motorbike and the idle speed is not steady at all.
    The model of my bike is Honda LS125.

    Thanks in advance!

  150. Hey i have a honda unicorn 2008 model. I have some serious problems with my bike. I find that there is a real lack in power. The bike does not run well in the 4th & 5th gear( in the top speed range). The bike does not cross 100 at all. I have taken it to the showroom n number of times, I have even ended up fighting with them. These guys were of no use. I have got it tuned with well experienced mechanics, but still it has no effect. there is lots more to explain, so is it possible to get ur contact no. I would be pleased if u looked into this matter & help me out.

  151. my bike Kawasaki wind125 goes upto 140km/h after installing k&N air filter i want more speed so can i modify or change (black)pipe between carborator k&N filter does works i have some different types pipes ________ ________

  152. Ashwini,
    I have Avenger 220, and u know it dont have tachometer. In this case how can I tune my engine? Please suggest. Bike not performing as it was before 1st service.

  153. hi ,
    i have a zma-R 2007 make , i tried to tune according to your guidelines. but i boserved a heavy beat and rough engine experience after i tuned it i also got less mileage in city and good avg on long rides. then i understood that its running on elan mixture, i again tried the whole thing once this time i tried to turn in the screw a bit more and it keep on turn in to a large extent but it was hard to turn the screw made it go to the last turn then got the screw turn out to get that optimal mixture. now bike is feeling smooth and pickup is also very good. seems it almost got that optimal AFR . fuel screw tightness is normal for all zmaRs or shld i apply some oil to make it smooth. guideme

  154. hi ashwani
    I changed silencer of my ybx after that my bike’s plug get black deposits on it.
    although it doesn’t give any problem in riding but the average is 35-37 kmpl.
    I tried what u suggested but the fuel screw is too difficult to move in ybx when engine is hot..there is not enough space to insert a screw driver..more over i am not sure should the screw be moved inside or outside as moving in is anticlock wise and vice versa you suggested opposite i guess.. please help my bike is already 37000+ run..

  155. Hi Guys…

    recently I replaced my Old Splendor with New Splendor +. It’s only 1500 Kms. Mostly I drive in City (10-15 kms a day) and rarely go for long drive..

    With my old Splendor, I was getting mileage of 58-60 kmpl. but after second service from my new Splendor +, I m getting only 46 – 48 kmpl. when I went to HeroHonda showroom, they say 48-50 is good mileage for city and need not do any thing.

    Can anyone pls help me on this.

    Dear Ashwin/ Sudhatma/ Amol: Expect some good guidance from you.

  156. I have pulsar 180, i tuned the volume control screw, Its working fine.
    sometimes swicth start doest work and kick start fails to start in single kick.
    sometimes it works fine.
    i turned clockwise to the fullest till the engine stopped, then slowing anticlockwise, to finalise the tuning to work

  157. Thanks for sharing, its really an Excellent article. I have Pulsar 150. After few services, I am not satisfied with the idling and pickup. I have consulted several mechanics in Bajaj Showroom in hyderabad and none of them has satisfied me. So I started doing the things myself. My Pulsar 150 (digital meter) gives milage of around 52-56 kmpl. Suddenly after few services, it started giving me around 46-48 kmpl and also I am not satisfied with Idling end engine noice. Following are some issues:
    1) Cold start is happening. I mean whenever I start my bike in the early hours (first ride), it switches off automatically if didn’t accelerate.
    2) After driving some kms, the engine sound is increasing. Making more noice.
    3) While in driving if I press the clutch, the rpm suddenly increases and then decreases.
    4) I have set the fuel/air screw for 2.8 rounds. It should be from 2.75-3.25 (please let me know if i am wrong) and Idling is net to 1000 rpm.

    Please let me know what i need to do to resolve the above mentioned issues. Thanks in advance

  158. Also, I have another question:
    I have tight the Fuel screw till the last and set idle screw to 3000 RPM. Then slowly I have turned 3 full revolutions of fuel screw anti-clockwise, then set RPM to 1100. Is this good enough for pickup and more milage?

  159. I have a CBZ extreme. I’m getting only 35 km/h at speed below 50km.I just covered 700km and finished 1st service. Now question is which kind of screw CBZ has air or fuel? Is it wrong or not to adjust the carb now. Your artical is very helpful, thanks a lot bro. Pls Answer me as soon as possible, I’m waiting…

    • Hi Rony, your bike is very new. You can’t know the exact milage right now. Milage will come in to picture only after 3 services or more. My bike is 4 yrs old and ran 48000 kms. I can give you an advice on how to maintain your bike. First you should not exceed 65 kmph for the first 5000 kms. Then after 5000 kms, you can drive the bike in your own way. The first 5000 kms is very important for any bike. Its like a new born child which you need to take care of. Nice example naa.. hmmmm :). I got this advice from a very senior mechanic. I followed the same way and even today my bike runs smoothly. So don’t go only in terms of milage. I strongly suggest not to play with ur bike in terms of Air Fuel adjustment or Carborator cleaning.

  160. Some tips for your bike:
    1) Don’t exceed 65kmph for first 5000 kms
    2) Maintain the speed, i mean 45-55 kmph
    3) Check the air properly for both the wheels.
    4) Change the spark plugs for every 10000 kms. Even if not damaged coz it costs around 60-80 bugs each.
    5) Go for long drives as you will know some idea about your bike (in engine heat conditions).
    6) Give regular service between intervals. 2000 – 2500 kms for each service
    7) Avoid breaks and use gears to stop. This way you can have better grip on the bike.
    8) Maintain same engine oil for each interval. I have been using Castrol Active 4T and you know it the best engine oil.

    • this also same happened with my bike i.e. hero honda pleasure a 4 stroke non gear i think it is the optimal tunning because my bikes performance is increased

  161. Ashwini,

    You mentioned….
    “You’ll notice that when you have turned it to about 3-4 full revolutions, the engine RPM slowly becomes constant. It is this point that you must stop screwing more. This probably is the optimal setting for your engine.”

    Please clarify if you mean 3-4 ful revolutions (360 degree turn – is a revolution)??????
    I could set it with just 0.75 revolution. Please reply. Am I wrong?

  162. i have pulser150dtsi,and im having air problem in my bike when i accelerated my bike. bike give me misfire and acting like fuel empty i clean my carburetor and fuel tank but problem still same.
    whats a problem

    • Hi Junaid,

      The problem might be with petrol over flow which will get resolved after few kick starts or might be with Spark Plugs which you need to clean/replace. Still the problem exists, contact near by Bajaj service person.

  163. hello,
    i have a hero honda pleasure 4stroke non gear i have tunned my bike i have got the optimal tunning of fuel screw at the 1 full rotation that of leanest mixture after this my bike is giving average of 35 on local and 55 on highways with economy speed but when engine is cold i have to kick it minimum 20-25 times to start the bike but others having same bike does not have this problem then give me solution for this problem of cold start

  164. hey,
    ashwini i also want to know how to measure the engine rpm ? which gadget is use for it? where i will get that gadget and how to connect it to my bike for to measure the engine rpm

  165. hey,
    ashwini i also want to know how to measure the engine rpm ? which gadget is use for it? where i will get that gadget and how to connect it to my bike for to measure the engine rpm
    as i tunned my bike with the help of engine sound

  166. At last i have found the site that clears most of my doubts. But 1 still remains, regarding the tachometer usuage to set the rpm, can i use the rmp meter on my p150 ug3 for it or shall i have to buy one. thanks for the article on carb tuning.

  167. Hi Ashiwini,

    Felt good after going through this post. This is really informative section for all the passionate bike lovers who do not want to leave their machines only in hands of bike mechanics and like me wish to do some stuff themselves, after all that is what they are passionate about.

    I want to know few things about Pulsar 150 – old model (2003 make)

    1. Does it have a Oil Filter
    2. Does it have a separate Air Screw to control Air Mixture other than Fuel Screw.
    3. Few days back my bike gave white smoke at very high RPM. But after I got both my valves changed it gives black smoke at very high RPM. I feel some tightness in riding the bike. It is not as smooth as it was before.
    4. Are there any bike engine flushing additives to remove carbon, if yes – what name and what is the process.

    I think some of my queries might be off track, would appreciate if I can get replies.


  168. i hav owned a suzuki shogun……i need to increase itz power….hav to tak it for racing…..plz tel me some suggestions to perform tat…..

  169. Thanks a lot ,
    While adjusting fuel screw i found few air bubbles coming from screw gap….is it a problem?
    and where i need to check the rpm of engine?

    once again thanks in advance

  170. hi frndz i have 2010 model cbz x with 8000 km my bike was fitted with k&n filtter and ngk irdum plug ,i see a article that if u want to beat karizma ,put k&n filter in u r bike so iwill fitted but my bike dont go over above 110 kmph, plz help me frndz reply me plz if any thing want to tune

  171. This site helped me. But it confused me as well. I am mentioning some useful points so that it will help those who want to tune their bikes.

    For 4 stroke bike with no tachometer (rpm meter):

    1. Increase the speed with idle screw to fast idle. It can be somewhat more than the normal idle rpm. The intension is to hear the change in rpm. At very high rpm, it’s very difficult to notice the change. This rpm is as per your convenience.
    2. Start the engine and turn the fuel screw clockwise to minimum position (full closed position). Your engine will stop. It may stop even before that.
    3. Turn the fuel screw anticlockwise by one turn (1/8 th or 1/16 th of a rotation) and try to start the engine.
    4. If engine doesn’t start, rotate by one more turn and try again. Engine starts with very low rpm. You can hear the same.
    5. Keep turning the fuel screw anticlockwise by one turn (1/8 th or 1/16 th of a rotation) at a time and notice the engine noise. At one point the engine noise increases substantially and engine runs at a high constant rpm. This is the point where you need to set the fuel screw. But, you will not find this point immediately. Even if you find, you will not be sure. Please follow the below procedure.
    6. Go on turning the fuel screw anticlockwise by one turn (1/8 th or 1/16 th of a rotation) till engine tumbles/stops.
    7. Now, turn the screw clockwise by one turn (1/8 th or 1/16 th of a rotation) and try to start the engine.
    8. If engine doesn’t start, rotate by one more turn and try again. Engine starts with very low rpm. You can hear the same.
    9. Keep turning the fuel screw clockwise by one turn (1/8 th or 1/16 th of a rotation) at a time and notice the engine noise. At one point the engine noise increases substantially and engine runs at a high constant rpm.
    10. Note the two positions (found out at the end of step 5 and step 9). Your optimum setting could be between these two points.
    11. Ideally, it should be the position, you found out at step 5. But, it’s difficult to hear the change in engine noise. Hence, if you repeat steps 5 to 9, you yourself will identify the optimum setting.
    12. The setting has to do a lot with the Jet size. Hence it will vary from bike to bike. For some bikes, it could be just 0.75 rotation from the full closed position.

    • Excellent article by Helper. Just have one query. What could be the possible reason if the engine does not stop even after the fuel screw is closed completely. My Access 125 had a slow pick up initially. After following the guidelines by Deepak, the scooter was like magnificent, I must admit I overdid the part a bit more, now the engine does not stop even after the fuel screw is totally closed, just comes to a slow speed. The scooter has run 2900 kms. Do you think I should change the carburetor? Please help. Took to the service centre, the guy does some things with the tachometer, and says the pick up is excellent. But I know, it used to be even better. He is unable to comprehend. Please help…

  172. Excellent article by Helper.
    Could you have any idea about how many rotations needed for my Pulsar 150cc digital meter 2007 model? I have set it at 2.75 rotations but the I am having the problem of cold starting. Even if it starts and didn’t accelerate, the engine stops. Could you have any idea?

  173. Generally, the starting trouble is associated with the Spark Plug. Even if the rod in the spark plug is consumed, the engine runs as sparks can be generated. But it gives a lot of trouble at start. So, first check the spark plug, then the idle rpm.
    For Pulsar, I have no idea. It depends on the Jet size. 2.75 rotations could be correct setting. You can confirm the same by following the above procedure.

    • Thanks for the reply. I have replaced the old spark plugs with the 2 New Champion spark plugs. I have still the problem of cold starts. If the engine is Cool, then the engine automatically stops. If I run my bike for 10 mins or 3-4 kms, then I am not having the problem. What could be the reason of cold start problem?

      • Jai

        Try to change the engine oil to Synthetic / semi synthetic of lower viscosity at cold temperature. If 10W50 engine oil is recommended for your bike then use 5W50.

  174. Excellent article.

    I have HH Passion Plus. When I adjust idle screw clockwise for correcting idling speed. Is this affect milage of my bike?

    I want to know where is my Fuel/Air Screew in my HH Passion Plus..

  175. one day after servicing….my pulsar 150 bike is giving an average of just 26-27 kmpl. I checked my bike with a local mechanic….he has reduced its pickup to repair its average. but it is still giving an average of 26-27 kmpl moreover it is running very bad….low pickup, low mileage…running very heavy.

    My question is that pickup is related with spark plug also because he has repaired my bike by opening its spark plug and how to bring its average back to 45-47 kmpl as it was giving before servicing.
    pls. guide me

    • Hi Vicky,

      The problem is not only with spark plug. Spark plug helps mainly in starting up the bike and pickup. The problem might be with the Fuel screw adjustment or with the clutch plates. Please check up the bike in Bajaj Showroom (highly recommended)

  176. hye
    i have fz-16, if u can please show me in a picture describing fuel & air screw.
    also in above note u haven’t mentioned, wht to do with air screw after turning it ot the leanest position.
    kindly reply

  177. Hello ashwini,
    Can u plz advice me how to set the carburettor for the hyosung comet gt250

    Pls guide me
    Thanks in advance

  178. Hi ashwin , i have red your post . it was nice. and i need some more clarification.I have my splendor plus new bike which which ran up to 6000 KMS with in 6 months .. and am getting mileage 55-58 KMPL . and this is not enough.. because some of my friends are having the same one but they are having the mileage like 75 – 80 KMPL… i want it to increase as like my friends and i drive my bike below 50 kmph .. what u have said in the above article is fuel screw clock wise and anti clock wise for air screw. but actually that is vice versa right… the fuel screw must be screwed anti clock wise to get low mixture of petrol and i don’t know about the air screw pls guide me to get more mileage……..

  179. Hi Archana,
    In your comment “Whenever I race up the engine, the rpm increases fast but very slowly comes down to idle. The mixture is not optimal, probably towards leaner side.”
    I am facing the same problem. So do i need to set the Fuel screw towards leaner side or richer side?

  180. Hi AshWini ,
    First Of All nice article i really like it.Help Me With This Plz I Have P220 dts-i. I Only Have top speed 122kmp maximum also have low accelaration..i Dont know why i cant reach 140 kmph or more..I dont care abt mile age ok .what shuld i do to have more top speed more than 122 kmph..How Many Turn shuld i give to Air/Fuel Screw to have much top speed..

  181. Hi i have a 2009 pulsar2220 .these days am gettin problem with my bikeits pick up goes down .engine hikups whil given race.local mechanic told me that there is sensor proble and its vry what should i do now am very tenses i cant ride bike over speed me guys

  182. hallo ihave hunk bike . i have problem of air/ mixture. when i chack my plug it always come gray black but not proper brown . is it ok the air fuel mixture in bike or not ? plz reply

  183. mr. ashwin .
    iam pleased to read the carb tuning. i just want to clear my doubt regarding my star city 100cc bike.i got it serviced from the local mechanic as it was giving explosions in the silencer whenevar i slow down bike from higher speed and the explsons when i press the clutch. it is quite embarassing in the traffic and is also giving low KPL. the mechanic says it is common for all tvs bikes but it did not happen to my bike when i got serviced through auth. ser.centre. my my vehicle is fitted with spaco carb.can u please explian the tuning with out techo meter as i dont have one thank u

  184. Mr. Ashwini kumar.

    I have a bike Yamaha G5 of 2 1/2 years and 30,000 km . At first it gives meilage of 54 to 58. slowly it is decreasing. when i ride in high ways also it is giving poor meilage. with sugession of mechanic i changed walves also. But no use. now it is giving 35 to 40. with your help i adjusted air screw as u say. now the engine is very smooth and comfortable at 2 anticlock wise rounds. but the meilage is same… now also it is giving 35 to 40. what can i do. please suggest me as quickly as possible.

  185. i have a doubt. i am planning on fitting a performance air filter and upjetting the carb. my question is should i do upjetting for optimal settings or just carburetor tuning (as mentioned in this article). which is the best solution because i dont want to running lean. pls help. i want the awesome sound and the trouble-free engine at the same time. and if anyone has details about a proper, experienced, and skilled mechanic in chennai, pls tell me his name and address.

    this is a wonderful article. we need not be dependant on mechanics anymore. thank you very much ashwini

  186. Hey ashwini,

    Hope you would help me on this.

    My bike is suzuki gs150r. I have rode some distance, then put the bike on centre stand and set the idle to 3k RPM. Now, when i turn the fuel screw clockwise, The rpm increases and when i turn it anticloickwise the RPM decreases….I am confused whether the screw is fuel screw or air screw? My bike is 4 stroke

    • Hi Keshav

      It’s fuel screw in GS150. The fuel mixture in your bike is on the higher side. You should turn it clockwise until the point the RPM stops rising further. You would find the sweet spot of your bike somewhat over there. Of course read and perform the instructions given by Ashwini carefully. I also performed tuning of my GS150 by reading this wonderful article.

      Many thanks to Ashwini for this very useful post.

  187. Hi Dear,
    I have read so much of replies, queries and comments. But it is seen that Apache RTR owner is very fewand this probably the reason that my queries were not get answered. I have an Apache RTR 180 which was just recently bought. Before that I used to ride my HH ambition 135 with excellent satisfaction and never feel the necessity of tuning the cars. But the case with my RTR 180 is totally different. From the very first day of bringing it from the showrrom i felt on the way home that the bike does not run smoothly at a constant speed of 50kmph, The bike hiccups.It feels as if the bike is not getting fuel properly or the time to rotate the fuel cock to the reserve side. I rotated the fuel cock but it is the same. I took the bike to the service station just at 290 km on its odo and explained the service guys about the problkems. But those gyus are really of little help. They took it for test drive and said that it is ok. I felt very much angry at them and later consoled myself. They does not feel the problem because they pull up the throttle excessively and at high RPM the problem does not occur.
    Aftere reading the Aswins article I make my mind of tuning the carb myself. But I found that at no point the Techometer remains absolutely constant. First time I tuned it and rode for two three days and found that the original problem has gone away.The bike has very good start and the idle RPM when it is hot is almost 1200. But now i feel that there is a drop in dragging power of the bike and the sound of the bike is a little bit unusual. So I am thinking of doing it once again.
    Now can anyone kindly suggest me
    i. Is frequent tuning will harm the engine of my bike as i experienced that tuning the carb causes a great stress on the engine .This is because i had to the keep the already warm engine running for almost an hour at about 3000 RPM. The engine becomes excessively hot and I fear that exceesive hot will damage the delicate and small parts of my engine.
    2. The RPM of my Apache RTR 180 engine is not constant any any poit. Is it normal or is there a problem with my carb?
    3. The RPM remains constant only whent I set the screw at the leanest possible point .But, here the RPM is very slow. Why it is so.
    4. Just today morning i again have done the setting. The original power has retunrned. But , now the engine has got starting prob. It needs 2-4 self to get started if the trottle not opened. As obvious, it is also not the optimal setting.Is the the setting in the leaner side?
    5. Will replacing the air filter with a K& N filer and setting the carb to the leanest will solve my problem?
    6. my odo is 1100 and i have poured castrol power1 at 1000km. is castrol powe1 good for apache rtr180 engine?
    kindly help me on these issues.
    7. my carb is probably mikuni bs29.
    with regards
    kushal Borah, assam

  188. keshav,u r nt turning ur fuel screw. U are turning the long screw that is for setting engine idel. Fuel screw is not long in cv carbs. It just looks like to be there for fastning the parts,i mean it is embaded in the body of carb. U can identify it easily by its color as it is made up of brass.

  189. I Have a 1999 model yamaha ybx and make more humming noise from engine side .I over hauled the engine and replace all bearing.please give your valuable comments to rectify the humming noise

  190. hey ashwini i had bullet electra completed 2 servicing n now i feel the carburator getting chilled after goes stop in traffic while m trying to accelerate.whats the xactly problem?i heard new carburator had a problem.pls help me….

  191. hi bikers, i am frm hyd
    i want to buy YAMAHA CRUX …
    i am looking for durability and mileage ……
    i am in confussion to choose. so,suggest me a bike equals in all aspects with crux.

    plz any one rply as soon as possible

  192. i hav a hero honda hunk with 10k km over
    now i am planning to buy an air filter(KNN)
    and also a spark plug to go with it(NGK)
    what do u guys suggest?
    should i go for oil filter(KNN) too?
    will it improve?

  193. i have taken hunk in march, now in sep i’ave serviced it there is some sound in engine mechanic says that u better change crank, is there another way to reduce sound??

  194. hey Ashwini it was a nice write up!!! i have one query. I own a Karizma and recently i’m facing a problem of my bike getting overflow frequently. Will setting the air/fuel mixture will help out? Or you have some other advice?

  195. hi
    I have suzuki samuri model 2001. recently i have serviced the engine with boar cutting, new piston, crank connecting rod replaced, engine bearings also replaced. carburetor jets-float pins also changed. almost in clutch side also every thing changed. After that i have ride it for 500 km in just speed of 40-50. after that now i am riding it for 60-70. but when i cross 70 i am not feeling comfort. means the bike is not getting stroke after when i am stopping some where. the smooth ideal dosent comes quickly. slowly the rpm reduces.
    suggest me how to tune it so that the firing will be fine and also the idel will also be smooth.

  196. I have a tvs apache,recently installed k&n air filters by removing the air box and hose pipe and fitting directly to the carb. bt im a bit confused about the other two pipes connected to the airbox,they are attached to the engine so im afraid if impure air enters the engine through them,so tell me what to do regarding this prob. ???

  197. Hi,

    I have this funny thing on my bike. The idle rpm and the bike jerks/gives hiccups when I ride without the lights turned on. When I turn off the light, the bike does not move smooth. When the light is on, the bike is excellent. What could this possibly? I have a bajaj pulsar 150 dtsi 2004 model.

    I’m planning to do the above mod and tune the bike. If I need to change the coil, what are the coils I need to change? Kindly help me out. Thank you.

  198. I have gone throgh ur veri nice article “Tuning Your Carburetor For Optimal Performance And Fuel Efficiency” U have cleared the very common problems of bikers. I have bike Bajaj 4-Strok Bike ” 4-S Champion” ( Model 1998). I was perfoming better before repairing it by a technician. Its Milage was above 60 before, and now less tha 50. I m too much exited to tune my bike myself. My problem is
    (A) I M NOT GETTING IDLE SCREW at carb. Can u guide me ?
    (B) How can I confirm that RPM is 3000 for this model ?

  199. i have karizma 2006 model the fuel screw yo are taking about …in my zma this screw is jammed what should i do to get it fixed .my bikes rpm goes up quickly n comes down slowly

  200. I am from Mumbai Borivali. Can u arrange an Airscrew of Unicorn Dazzler? My dazzler Airscrew is broken and I am not able to find it anywhere not even at Honda Service center.

  201. sir,
    i’ve HH HUNK (april-2010) run approx-5000 km
    according your article i try to Tuning…
    fuel screw at 2+(1/2) turn RPM increases high…i set fuel screw at
    that position ……
    is it perfect setting..for High mileage please reply SOON…….

  202. I just have fitted my passion pro with two electrode spark plug. Now my bike has increased pickup and acceleration, its aint feeling sleepy anymore. Did anybody know if there are any side effects of using two electrode spark plug for a 100cc bike.

  203. I’ve pulsar 150 dts i.i tried tuning my bike since it’d shut off every now and then.bit after tuning it’s giving out very bad smelling gases.wat cud be the problem?

  204. Mr. Ashwini Kumar,

    Along with other informational website for mileage / fuel efficiency tuning and maintenance, i.e., your’s is more practical to understand for local condition.
    I have a old LML Vespa Select II Scooter to manage my life, and got the theoretical part of tuning methods from you, earlier I left it to scotter mechanic but he was tired for my specific need for better mileage, so learned myself by trial and error, and you give practical theory of how-to tune, though you wrote for Motorcycles, it is useful for me too.

    You deserve lot of thanks, indeed you help others and help economy by reducing expenditure on fuel costs.

    Very best regards,
    Kannan N S

  205. @all plz
    move the idle screw also(throttle screw) to bring it near stall condition.
    this is done because all bikes hav different setting done so to reset this this is done.
    when u add more fuel,for the newbies, chack the tachometer for where the needle resonates less(range of resonance is less) that is ur ideal steeing

  206. hi aswin

    does the milage of the bike goes down if we clean the corborater ? my friends said that if we clean it the milage will fall down ? is it true ?
    i am waiting for ur reply

  207. hi aswin

    does the milage of the bike goes down if we clean the corborater ? my friends said that if we clean it the milage will fall down ? is it true ?
    i am waiting for ur reply

  208. @keshav,
    i think your mixture is on richer side.
    on all 4 strokes it is fuel screw towards the engine.
    even on my discover135 which has keihin carb its brass in colour and towards engine.
    thank you very much for a great article.

  209. thanks.

    i got 75kmpl with my splendor plus with alloy wheels .my bike is 4 years ols.i only experience tappet noise when my engine gets heated after 20-25 kmpl.please advice me.for stopping tappet noise

  210. hi deepka ,i red this article and came to a conclusion of tuning my bike myself for the AFR. i did everything correctly many iterations but i notice 1 thing which is not suiting . you mentioned a sweet spot – ” u should turn the fuel screw clockwise till the RPM meter comes form 3000 to engine shutdown point(nearly) and then turn it “anticlockwise” ,then then the response will be the engine raises till a point which settles at constant ” . i did the anticlockwise screwing very very slowly and then too i cant get that sweet solid spot where the engine idle will be constant .
    hence i tuned the fuel screw(golden colour) anticlockwise till a sufficient poin which i felt somewhat constant idle and turned the air screw to 1200 RPM . my bike is a PULSAR 22O, does high cc bikes need some more specification in carbarator tuning…! , please guyz let me know if any ,im relatively new in tuning my bike and i care about my bike very much . since every time i dont want to go to a local mechanic and tune my bike(becoz he works for money), i decided to take care of my bike myself hereafter. please any one suggest me a solution. im counting on u deepak raj. thanks in advance..

  211. Thanks a lot Ashwini Kumar,
    This article really helped me in tuning my bike, i own a Honda Shine clocked 12000km in 9 months. My daily running is nearly 60-70kms.
    i tuned my carb to little leaner side and the result was amazing, my bike gave me 61.53 KMPL.
    and there is no drop in perfomance. Earlier i was getting 52 KMPL.
    i always drove it between 60-70 KMPH, and now i have also replaced my stock spark plugs with NGK G-Power yesterday. Result is good, lets see how it make difference to Mileage.
    You guys are doing a great job, keep it up.
    Thanks once again.

  212. Dear sir, after tunning the carburetor, my pulsar looses the power at speed of 55 to 60 kms, suggest how to recover with this

  213. hi
    i got glamour which is about 1.4 years (7000kms). its milage is poor . it bearly reach 60kms/hr . i dont know how to tune its carburator because glamour dont have round per meter . more over hero service center dont give much attention to this problem . my glamour is no more like before . i have to try very hard to start it . some time it stop in middle of traffic. is it carburator or engine problem . if it is carburator problem how much do genuin hero glamour carburator cost i want to replace it .

  214. Hi Ashwini,

    I have a strange problem with my Pulsar 180cc UG3 (40000 KMs done). Apart from this problem there are no issues with my bike at all. Let me explain you in detail.
    After driving my bike for some time; vacuum gets created in the fuel tank so the petrol doesn’t flow to the fuel pipe from the fuel tank. Earlier I used to face this problem once in every 2-3 days (Around 70-80 Kms run) but now I face this problem 2-3 times a day (30-40 Kms).

    I took out a simple solution of this problem. I open the fuel tank for 6- 10 seconds whenever I’ve to go somewhere and the engine performs well after this.

    To add to the problem; if I drive by bike and then make it rest for 30-40 mins and then while driving back if I start the bike again (Self Start) and forget to open the fuel lid; the bike stops after 500 Meters. At this point I open the lid and the bike starts in 1st go.

    What I can figure out is that the small hole inside fuel tanks (to rinse the rain water) is blocked so the air may not be flowing in. I checked in with some mechanics but I still face this issue. I tied to clean that hole but its so tiny that I doesn’t I guess.

    I’ll tell you about my driving habbits so that you may get some more idea. I fill the petrol from only one petrol pump every time. I fill arount 7- 10 Litres so that I don’t have to worry about petrol. I use a petrol lock and always turns it off it after I reach the destination. I never leave it on Reserve or ON state. I changed the petrol lock thinking that the lock may be faulty but this problem still persists. I always kick start my bike in the morning or if I drive it after 4-5 hours. In the morning I drive a bit faster (around 70- 95 Kmph) as I always get late and has to rush to the office :). While coming back from work I drive like I am sitting on an elephant. Very slow, steady and calm (40- 55 Kmph).

    Please help and suggest me a perfect solution. I am tired of opening the fuel lid time and again, sometimes it is frustrating and embarrassing to do in the traffic.

    Apart from this my bike has no issue. No performance issue, no acceleration or breaking issue, nothing at all. My 180cc is a very good performer (Provided petrol intake in engine is running perfectly)

    Please E-mail me @

  215. Hi can you please make a youtube video for this..will be much more helpful to point out the idle scre and fuel/air screw… and the engine sound to hear.

  216. I once set it up randomly then when I went for a long tour, after 3-4 hrs of riding it started to over flow in carb.. did I do “rich” mixture ??????

  217. i am student of engineering, please let me know the exact
    turn to tune my YAMAHA YBR110, I had tried a lot. But not
    succeeded. I want this bike to its best mileage 70-80 as per company says. but i never got at least 65KMPL on road.

    Which is the best speed for best mileage? I am currently running on 60KMPL continuously.

    Please let me know how much turn i have to rotate the Both Air and petrol Screw.

    Thanking you

  218. I am an owner of pulser 150,2005last model,(old tail model),earlier i am getting a milge of 45-50kmpl,but after engine boring i got mlg of 30-35kmpl,i showed it to mechanic after 1000km after boring and ask him to tune to best. Mlg,but result is same 30-35kmpl,i was woried and going to sell IT,AND as a last work in my pulser i have tightened the screw at the bottom side of carbeurtor and
    loosen the fuel screw whch have a spring that connect the accelator cable near carbeurator.Nw my pulser mlg is 55-65.OnlY PROBLEM IS WHEN IN TRAFFIC I HAVE TO RAISE OTHERWISE ENGINE STOPS.Is this gud to bike,i managed not to stop in blocks by optinum acceleration..My question is is this kill my engine.If yes what should i do.

  219. I am an owner of pulser 150,2005last model,(old tail model),earlier i am getting a milge of 45-50kmpl,but after engine boring i got mlg of 30-35kmpl,i showed it to mechanic after 1000km after boring and ask him to tune to best. Mlg,but result is same 30-35kmpl,i was woried and going to sell IT,AND as a last work in my pulser i have tightened the screw at the bottom side of carbeurtor and
    loosen the fuel screw whch have a spring that connect the accelator cable near carbeurator.Nw my pulser mlg is 55-65.OnlY PROBLEM IS WHEN IN TRAFFIC I HAVE TO RAISE OTHERWISE ENGINE STOPS.Is this gud to bike,i managed not to stop in blocks by optinum acceleration..My question is is this kill my engine,how.If yes what should i do.,no other problems im my bike ,bike is in great condition otherwise…

  220. I drive a gilera motped and i put 2 stroke in it after that the bike started actup i turned the big brass screw and the bike went in to a hi rev what do i do to get it to normal please help

  221. Hey ashwin,
    I am a 2010 pulsar 220 owner and i am not able to find the fuel screw,is it the screw next to the idling screw,if not what is that screw.
    Pls shed some light on tis.

  222. Hello,

    I’m not able to figure out whats the problem with my pulsar 150, sometime it get starts in one kick and sometime i have to kick it for several time to start the engine, I’ve showed this to mechanic he is saying there is a problem with Carburetor and also not getting mileage. I’ve installed new exide battery but not getting self start. I’m getting frustrated because of this please help me….

  223. my tvs centra 100cc bike misfires while riding. It misfires randomly , not regular and not frequent as well. Mostly it will misfire while i am changing gear from 4th to 3rd gear(slowing down) or vice versa(speeding up). Is it a problem with tuning or something else? like it needs oil change or servicing?.
    It was serviced 6 months ago, but problem is there from 3 months. I only ride 10 km/day on avg. The problem is faced after 3-4 months from each servicing.

  224. I own a 250 cc Ideal Jawa motor bike. I want to replace the cylinder bloc
    but can;t find one. Could u help me to find one cylinder bloc. Please help.

    Thanks and best regards

  225. I own 250 cc Ideal Jawa motor cycle. I want to replace the cylinder bloc.
    Could u help me to find one. Just send me the email/tel no./address of the
    vendors and I shall contact them.

    Kindly reply by my email id.

    thanks and best regards

  226. HI,

  227. hi i own a karizma r just 4 months old run about 2000kms and was running fine, all of sudden the bike dosent start unless choke is fully open when choke is closed the engine stalls. any help….. and for tuning can somebody post the picture of air screw in karizma.

  228. hello alll brother,,
    i have splendor plus ……..i m follow these settings but when i round fuel screw clockwise then fuel is rich..and when i round it anticlock wise then fuel is lean…so according to given information its just opposite…can anyone help meee….bcoz my bike milege is very poor…in city35 to 40kmpl and on highway maximun 50kmpl….on 45 to 50kmph speed

  229. Hi

    I read the article, nice and informative, i have karizma R , my bike didnt move freely needs adjustments, will do it as per your instruction, once again the said information is very useful.


  230. Hi, I’ve Unicorn 2005 Model and the engine is really screwed.
    Some one please suggest me good Mechanic that can fix my bike.
    I tried many local mechanic and they just screwed up my bike more.

  231. Well thanks for the Blog,
    My street used to never cold start without a choke,
    and also used to race a lot in idle, the idiot mechanic (probably) messed up.
    Now i have tuned it and it is as smooth as anything!!!
    It starts with a single kick/ Self in the morning too 🙂
    and dosent even race much. the fuel efficiency has been raised to 61 km/l in city!, which it first gave 54!! 🙂

  232. hi, friend I tuned my yamaha libero as ur instruction and I really feel change in its sound and starting problems as well as milege.
    thnku very much

  233. hey ashwini,

    how to tuneup my honda shine carburator. air screew in inside-my screw driver not reach to the air screw.

    please help me.

  234. my bike bajaj discover dtsi 100cc ,its give 50 kms milage when i open the plug then i found that my plug round wall black but in middle elctrod position is copper
    clour what i do for better milage and trobule free start

    thanks you

  235. Hi.. I own a cbz xtreme 2011 dds model. I get a overall mileage of 30. Thats a very low fuel efficiency. So after reading this article i tried tuning the carb myself. I found both the air screw and fuel screw. But the fuel screw is fully tight. I am not able to loosen it. I think so i’ve chose the wrong screw. Pls help me wit this. Which is the fuel screw. I dnt knw any mechanic nearby and i just can’t ask the service centre employees as they never open their mouth if i ask any doubts.. Pls help me with this!

  236. Friend,

    I have tuned my bike (Splendor Pro) as per the above mentioned procedure but the bike is now giving hiccups during cold start & also when I ride in 1st & 2nd gear for the first time. But when the bike has covered some 1-2 kms then everything is normal & bike becomes very smooth.
    Also I have tried starting using choke but the bike doesnot start even.

    So what could be the possible reason

  237. Hi frnd thks for ur advice i did the tunning as u have mentioned in the article but my rpm is little unsteady as i hav moved 4 revolutions anticlockwise but as i moved 5 revolutions the rpm gets steady so can u plz sujest waiting for your rply.

  238. Hi Ashwini,
    I have recently purchased a Suzuki GS 150 R. I want to check its mileage therefore I go follow the conventional method ” reserve to reserve ” to check the bike’s mileage. But i am facing a strange issue with the fuel cock. At reserve I note down the reading then fill the measured quantity of petrol and then check for the KMS run to calculate the KMS run per litre. Sometimes what happens …. when the reserve point comes I have to turn the cock towards RES. position. But if after some time if i park it somewhere for an hour or two, if i again turn the cock towards “MAIN” position even then it goes for many KMS not just 1 or 2 KMS. Is the cock faulty or what ….. i am very confused because at the time of reserve I make it very sure that it is not going to move forward in the “MAIN” position. Still how is it possible that I can move it in the “MAIN” position after sometime? PLEASE ADVICE ME!!!

  239. hi ahwini ida stunner which i bought 2 months back.before 1st servicing my bike’s mileage was around 50km per litre but soon after 1st servicing it has reduced to 35-40 km per litre,i complained them twice thrice but it did not changed,done with 2nd servicing complained again but still its 40 km per litre can u help me?

  240. Hi,
    This is karthik and i have a hero honda hunk model 2011. My bike have several problems since i bought. The speed reaches 46 kph smoothly, But trying to go faster is more critic. It starts vibrate and feel going very faster in sound, but the bike never move as that. It pushes very slowly to reach 60kph. And riding bike in slow speed in traffic ie.3 gear is also hectic. It gives again trouble in this case.

  241. I have a Bajaj Platina 125cc.
    It low in mileage and gets hiccups after the last service at 10 000kms.
    I want to tune this now.
    I have found 2 screws in the carb. One is bronze and one is in silver colour.
    They should be the fuel and air screw.

    But… where is the idle screw? I couldn’t find it!

    Also this bike doesn’t have a tachometer. So how to check the RPM?

    Please help me.

  242. hi ashwini i have tvs apache rtr 2009 it gives me a mileage of 30 and the engine heats early.and gives missing while riding please tell me what to do.

  243. Hi Deepak,

    I recently tuned my Bajaj Platina by the technique mentioned by you as my local mechanic had screwed it due to which average of my bike came to 60 kmpl from about 78 kmpl 🙁
    It worked great!!! After tuning my bike, it again started giving average of 80+ in city!

    Thanks a tonnnn dude!

    Keep posting such articles.

    • For TVS GLX 125

      1.25 turns of air screw is the normal mixture with spark plug from Champion.
      You will get mileage around 62 on highway and around 58 kmpl in city

      If you open out the air screw till 1.5 to 1.75,you will get maximum mileage of around 70 kmpl on highways
      Dont expect mileage more than 70 from this bike with optimum settings
      I own this bike and I have tuned it hence based on this,I am able to answer your query

  244. sir,

    what do you mean here “Do not just leave the engine idle and start with process. I mean it. Ride the bike.” Bike should be in 1st gear or it should be in neutral while the process is going on.

    • no buddy…… he sed before starting with the process get a long drive possible atleast half nd hour nd let the engine heat adequetly…….he mentioned it in dat way coz sm ppl will just put their bike on centre stand nd the idle the bike. which is not correct. then once ur engine is warm put the bike in neutral nd then start with unscrewing process……

      i did as he sed….and like others i found the rpm rising once we unscrew from leanest position -> then constant -> the starts decreasing…but not sure when to stop unscrewing. Will have to make sure by looking at spark plug then only we can determine perfect tuning.

  245. I have tuned my carb but feeling like more lean correct it should i repeat the whole process given in article again or can i adjust the fuel screw …?

  246. Dear all,
    My discover 100cc dts-si 2012 model, just drive only 2300KMs, but that gives only 65 KMPL, please help me to increase my milage.

  247. Hey there..I Got a new apache rtr 180 3 mnths ago and when the engine is heated up like after 5 10 kms, when im standing at signal,during idle, the bike revs start going down like from 1400rpm to less than 1k rpm.nd when i throttle the bike stalls…what should i do?

  248. Hi Ashwin,
    I have pulsar 150. I have modified its Carburetor to old japan made Carburetor its working nice but having some problem with it. In running position spark cut off takes place n bike turns off. I am not getting the reason for it. Is it because of fuel supply or any other reason. mostly it happens in 2nd & 3rd gear.

  249. Hey Ashwin,
    I own an Avenger-200Oil Cooled(2009). Of late the engine gets overheated even after 15-20.mins of smooth riding. I got all possible reasons checked/replaced but yet the issue prevails. Tuning carburetor hasn’t helped either. Any ideas??

    I am planning a long ride 1 in Dec end & one in Jan. Plz advice before that.

  250. hi i bought Passion pro 3 months ago,the engine sounds much in 2nd 3rd gear,sumtimes ther wil not be too much sound,my bike stops suddenly sumtimes,and the main prob is when i change gear fro 2nd to 3rd in a speed of 25kmph or 30kmph sumtimes it acts like i changed gear from 2nd to 1st,then if i again press gear it becums properly,wt is the prob solution pls

  251. help me out man.
    I tried this process with my bajaj discover 100cc and now the bike shuts down while slowing down. I took it to the nearest mechanic and he claims it is due to carbon deposition in engine and i need to decarbonise it.

    the bike has run around 27000km so far and is regularly serviced at bajaj service station. Should i decarbonise the bike?

  252. i have passion pro. just drive 2100 kms. i have a doubt in setting idle screw in 3000rpm or 1000rpm as you mentioned. because passion pro has not rpm meter. how can i solve this problem. thanx your post . its great.

  253. nice article. 🙂
    I got one problem. I own a Suzuki Fiero model 2000 with more than 100000kms on the clock, ya true it is one lakh. i changed the carburetor at 80,000kms. The bike is running fine and returns me around 53 kms/ltr in city conditions, and around 62 kms/ltr on the highway. But when the engine is operating at the full warmed up conditions the engine seems to ‘hunt’, i.e. the idling goes brrrr …..brrrr up and down just like the ill-maintained trucks of yore. what could be the reason? Otherwise the m-cycle is running fine except for the irritating idling.



  254. I have yamaha szr 2012 model almost 7500kms riden. I have poor mileage prob. Manyatimes I’ve got tuned from mechanic and also self tuned carb and noticed a mileage about 57km/l while mileage checking for almost 10km ride.
    But at highway on long rides every time about 28-35km/l while spark plug was quite white.I used to ride from my childhood and I am a perfect rider,used many yamaha bikes but faced mileage prob only in yamaha szr while used your technic.
    Plz solve my prob to well tune the carb and also mail me
    Waiting for solution…

  255. Hi ashini,my bike is hunk digital,crossed about 9700 km. i tried ur method but when i turn my fuel screw nothing happpens. Why it does,i warmed it very well,pls help me. thanks

  256. I have a doubt.. my fz 16 was giving an average of 35kmpl approx. Then sum1 messed with my petrol pipe so i got a petrol lock put up. The bike has run close to 14000 km. ALL OF A SUDDEN MY AVERAGE HAS DROPPED TO 20 KMLP..!!! Please suggest

  257. I have installed k&n rc1060 model air filter for my suzuki access 125 (filter box kept open).after fixing air filter the scooter dosn’t get started on morning(cold startE. And also missing are seen,while driving .also nt able speed up above 60s scooter . Is thier any remdy for my problem. If yes please do mail me at or contact me please nw its too difficult for me to ride my scooter.

    • Dany,
      KN filters supply more air than a stock filter.Which means you are running on a lean mixture.Try tuning the carb on a slightly optimum or richer side you should not be getting those problems again.Also try to check the spark plugs. This should help

  258. thanku for givin such a exellent awsome article.

    i have installed k&n air filter rc1060 for my suzuki access125 filtr box kept opened to get good air flow(done from local mechanic in our distict). Aftr 2000 km now there is a difficult in starting the vehicle at morning need to be kiked or by selfed for 5-10 times. And pulling power initial pickup have came down. Sxooter is showing missing while running. Also not able to go in higher speed due to this.
    Is there any remdy for this…
    If i rejet carburator, once again problem will get solved…?????? Plese replay for my problem…u

  259. Hi,

    I own pulsar 135 LS . It is having vibration issues. Is there anyway that i can refine the engine just like what honda guys do ????

    please tell me …

    Thanks in advance.

  260. I have bajaj ct 100, it starts with one kick even in cold morning. But after getting its carb cleaned by a local mechanic i am facing some problems.
    1. My bike feels like it is loosing power, like it is not getting enough petrol.
    2. It de-accelerate very quickly when releasing the throttle and slows down very quickly and when i pull the throttle it accelerates quickly as the engine is using so much power for pick up. So the engine feels so rough. It used to be a very smooth engine.
    What tuning should i do? Rich or lean?
    It has got kehin carburator.

  261. Hi, im using pulser 150cc nov 2012 model. I have completed 2 services. Normal riding speed is 60-80kmph. Last time when told the service person to tune my bike mileage. Only for the first time I got some where around 55-60kmpl & regularly use shell unleaded petrol. After getting that mileage I used some other company petrol only for 1 time, from that time onwards its again came back to normal milege 40kmpl. I just wanted to increase just by 10kmpl more. Can u help me out plz.

  262. My CBZ is 1999 First model(July). I am getting 39.1212/ KM. Daily i used to go 15 Km with average 70 Kl m/ Hr ( On High way). While return the average speed is 55 – 60 K ml/Hr. When ever i cross 60 Km/Hr barrier there is some vibration on the bike and it continues upto 70 K ml/Hr limit then it disappears. Please can u suggest me the cure? many thanks.

  263. This article is very good. I ride apache RTR 150 and it vibrates a lot when ever I try to go for 80-90 km/hr. can you suggest me a way to reduce the vibration?

  264. hey Ashwini hi.
    I’m using Suzuki GS150R, im unablet to tune the carburetor as u mentioned above.
    i’m bit confused. can u pls make a video of it? as most of the people are asking to make a video. it would be a bit more easy.
    my bikes air screw is at the left side and the rpm screw is at right side. it differs in some of the bikes isn’t?

  265. What exactly mean by hiccups?
    I want to know more on relation or how to read engine condition and milage from spark plug colour?

    I own honda cb unicorn 2010 model, from pune.

  266. The article says about the analog rpm meter, what should be done in case of digital rpm meter? will the digital meter also show the unsteady state when tuning is started

  267. Can anyone tell me what does one full turn of air/fuel screw..?? is it 180 degree or 360 degree…??? i own pulsar 180 ug4 with speed lines. clocked 28500Km since dec 15 2011.

    • 1/2 turn = 180 degrees turn
      1 full turn = 360 degrees turn

      for the tuning to be easy and you will not be confused:

      always start 1/2 turn, relax, don’t panic and don’t be hasty.

      example: 3 full turns (since 1/2 turn, 180 degrees every turn)

      1/2 turn + 1/2 turn = 1 full turn
      1 full turn + 1/2 turn = 1 and 1/2 turns
      1 and 1/2 turns + 1/2 turn = 2 full turns
      2 full turn + 1/2 turn = 2 and 1/2 turns
      2 and 1/2 turns + 1/2 turn = 3 full turns


      6 half turns all in all

      that’s it. 😀

  268. Thank You Very Much Ashwini Kumar for this nice, wonderful and useful tutorial on how to adjust and tune up the carburetor (especially on my Yamaha SZ-R’s Mikuni carb)… I followed your tutorial step by step and the result is great, awesome and astonishing… I cannot believe it up to now that I successfully do it… The tune ups that the mechanic had done was not optimal and perfect, but now, the engine is humming perfectly. No more hiccups. One click on electric start and one kick on kick starter (without opening the throttle) and the engine runs smoothly. Engine sound is stable and the throttle response is quick. I will report my future observations after I test drive the motorcycle tomorrow.

    So here’s what I do:

    1. Warm up the engine for 5 minutes… (every morning)

    2. Run the motorcycle for 15 minutes (40 – 60 kilometers per hour on speedometer)

    3. Prepare a flat head screwdriver and center stand the motorcycle.

    4. Increase the idle speed by turning the idle screw clockwise (direction of turning is going to the carb or to the motorcycle. Idle screw is located on the right side of Yamaha SZ-R Mikuni carburetor, upside down with spring. I did not reach 3000 rpm, only up to 2800 rpm on the tachometer.

    5. Using the flat head screwdriver, I turn the fuel screw clockwise or inwards until the rpm decreases to 1000 and I stop turning it as the engine shows signs of stalling. After that, I turn the fuel screw counter clockwise or outwards until the rpm increases back to 2800 and the needle position in the tachometer is constant and not moving. The fuel screw is golden color located on the left side of Yamaha SZ-R Mikuni carburetor.

    6. Finally, I turn the idle screw counter clockwise (direction of turning is going to you or away from the motorcycle) until the rpm decreases to 1000. So, the idle speed is 1000 rpm only.

    So that’s it. Simple as it is. Good luck to all especially to my fellow Yamaha SZ-X / SZ-R / SZ-RR owners. To God be the glory. 😀

    • Hi Ashwini and Cedar,

      I have a Yamaha SZ-R, 3 years old. I have a longstanding problem with my bike. While riding, whenever I apply brakes and lower the throttle because of traffic or humps and potholes, my engine turns off. I have ridden about 30000 KM. So I do have a basic knowledge of keeping the gears, throttle and brakes in sync.
      Now I have tried Yamaha service center mechs, local mechs, popular mechs but none of them have been able to fix this particular issue. All what they have done is try to tune the carburetor but seems no one got it right. Either they increase the idling which drops the mileage or reduce the idling which improves the mileage. But the main problem of engine turning off whenever slowed down is still there. It’s been there for about 1 year. For fixing this problem, getting the right carburetor tuning will help or any other reason can also be there ? Kindly advise. My e-mail:

    • how many kilometers per hour is your speed. is it steady?

      mine is 35 kpl on 60-80 kph, sometimes 40-50 and 90-100 kph after doing the carb tuning. follow what I had done. the best is 3 and 1/2 turns or 7 half turns from the leanest to richest.

      always remember, the richer the better. meaning engine will not overheat fast while on higher rpms and warm weather and cool faster after use, faster acceleration and torque, hiccups will completely disappear, quick throttle response, smooth engine and good sound and longer engine life.


      you can turn the fuel screw clockwise to make it lean so less fuel consumption
      turn the air screw clockwise also to make it lean.

      fuel screw = pilot jet for 4 stroke motorcycle
      air screw = pilot jet for 2 stroke motorcycle


      please read the links below (very helpful):



      • original sentence: turn the air screw clockwise also to make it lean.

        correction: turn the air screw counter clockwise also to make it lean.

        sorry. my mistake. typographical error.

  269. Make and Model: Hero Super Splendor 2012#
    1. My bike hiccups.
    2. In the top gears my bike feels like it is loosing petrol while acceleration goes low due to bumps ahead and re-acceleration to be started by me, feeling like that the throttle wire is being cut.
    3. At the morning it starts quickly but the condition stated above appears more aggresively bad than other time in the day.
    3. Many times the engine become off when the bike is on 1st gear.
    1. Which type of screw is used in my bike air or fuel?
    2. What is the tuning direction in case of my bike? (Richer side)
    3. How to solve the above problems (without a tachometer as I dont have tachometer)?
    4. How the Engine be a less sound engine like a new glamour?
    …..Please please help me.
    Thanks in advance.

  270. I got a petrol leak thru d hose below, when I turn air screw anti clockwise. my bike is CB unicorn. I only got only 40km mileage now from last year I bought. pls help

  271. Hi,
    I have an Fz, which i was very much satisfied till a few months earlier… I had a shortage of mileage and led me to install an K&N filter. Ever since the installation the performance was quite outstanding… better pickup, better mileage,better at drag races,blah blah… Bt it did not last long [my bad 🙁 ].
    I had a problem of throttle missing at lower rpms when it comes down from a higher rpm. My normal gear shifts are nearly at 6000rpm. But,when i throttle beyond 8000rpm at fifth gear and come back to a stop or at lower rpms, my engine stops!!!! there will be no acceleration at all. Then i have to wait for 5 mins by switching on the choke, and then i can run for a couple of kilometers. I asked it to my friends who were using K&N(both yamaha and other company), they replied that they had the same problem, bt only after driving more than 20000km. The problem got worse by now, as i cannot accelerate beyond 3000rpm!!! This is totally killing me….
    NOTE: i have tried to tune my bike at all possible positions of air screw.
    Any good ideas to over come this hectic problem?

  272. Good news to all owners of Yamaha SZ16/SZ-R or any versions of SZ and FZ16:

    if your motorcycle performance becomes worse or consumes too much petrol (gasoline) after following my way of tuning the Mikuni carb.

    Here is the way to restore its performance and gasoline consumption to the nearest factory/default setting.

    i followed this tutorial:

    1. Warm up the engine for 5 minutes… (every morning)

    2. Run the motorcycle for 15-30 minutes (40-80 kilometers per hour on speedometer)

    3. Prepare a flat head screwdriver and center stand the motorcycle.

    4. Increase the idle speed by turning the idle screw clockwise (direction of turning is going to the carb or to the motorcycle. Idle screw is located on the right side of Yamaha SZ-R Mikuni carburetor, upside down with spring. This time, only 2000 rpm.

    5. Using the flat head screwdriver, I turn the fuel screw clockwise or inwards until the rpm decreases. I stop turning inwards as the rpm becomes 1500. The total number of inward turns in my case is 4 full turns or 8 half turns. Do not tighten too much as you will damage the tip of the needle and you will be screwed. After that, I turn the fuel screw counter clockwise or outwards until the rpm increases back to 2000 and the needle position in the tachometer is constant and almost not moving and the exhaust pipe’s sound is like high but low and steady and crisp. The fuel screw is golden color located on the left side of Yamaha SZ-R Mikuni carburetor.

    6. Finally, I turn the idle screw counter clockwise (direction of turning is going to you or away from the motorcycle) until the rpm decreases to 1000. So, the idle speed is 1000 rpm only.

    So that’s it. Hope this helps. To God be the glory.


    HINT: if the tuning is right, everytime you startup your bike(which is after warmup), pressing the electric start without moving or opening throttle, the engines runs smoothly and automatically without stalling or whatever.

    CAUTION: always use the kick starter on every warmup everyday. warm the engine 3 minutes minimum and 5 minutes maximum. after warmup, then you turn off your bike, then that’s the time you use the electric start all the time the whole day as you start the bike again. since our battery is not maintenance free, when we use the electric start every morning every warmup when it is cold, the water level decreases compared to using kick start every warmup that the water is level remains ok. but if your bike has no kick starter, then never mind and never worry.


      on step no. 5, the number of turns counter clockwise or outwards is 2 and 1/2 full turns or 5 half turns in my case.

      if you are not sure of what you do, then ask assistance immediately or bring a good mechanic with you to do this tutorial.

      on step no. 6, it depends on your preference and the default idle speed of your bike in the owner’s manual/service manual. you can choose from 1000 rpm to 1400 rpm or whatever as long as the rpm will not go beyond the default setting.

      good luck to all.


    • You’re welcome Prasanth. My pleasure and honor to share my knowledge & ideas to any fellow motorcycle riders.

      An overwhelming accomplishment and i am overjoyed.


  273. Hi,
    Iam having Bajaj Caliber 115 which is giving me very low mileage.On fuel screw i tried all positions including below never find the spark plug colour on black or yellow or brown.

    Below are the steps i done.
    1.Adjusted the Fuel Screw anti clock(open) wise untill i get the maximum RPM.
    Responce on BIke:
    A.Very Good Ideling, even at 750 RPM engine will never die.
    B.Running is very Slugish and i have to open the throtle 1/4 for smooth ride at this point rpm will be at 5500, so driving below 50 will be worse and vibration is very high, like hamering inside the bore.
    C.Low mileage
    D. No enging over heating, Normal Heat (not very low)
    E. SPark plug is in white colour(ceramic part), Lead is in rusted iron colour.
    F. No smoke and no black ash deposite in the silencer end it is very clean
    2.(Adjusted the Fuel Screw anti clock wise untill i get the maximum RPM) from this posstion i given half to one full turn clockwise turn.

    A.Engine is very smooth and no vibration
    B. Still low mileage
    C. Even if you fully release the IDeal screw engine is runnig at 100o rpm after 5kms it will be 1250 to 1500 Depends upon weather.
    D. Engine Over heating
    E. RPM will not come down imdly after relesing the throttle.
    F. Piston is running like air compressor, no hammering effect.
    G. able to hear small valve sound after 10 to 15 kms.
    I never find a black or brown sparkplug, What will be the problem anything on the below.
    1. Carb leak or Air filter Leak (manifold or airfilter to carb joint rubber)
    2. Ignitation timing
    3. Read switch (for CDI with magnet attahced to throtle cable)
    4. Ignition coil
    5.Spark plug (tried in new plug also)
    6. Clucth
    7.Valve alignment

    Till now the below repairs have done but no improvement.
    Bore and Piston Changed(Regular size)
    Clutch Plate set full kit.
    Carburator Changed (from another Bike)

    Canyou tell me based on your experiance which part we have to attack.

    • 1. air cleaner – clean / replace

      2. carburetor – clean / adjust

      3. valve clearance – check / adjust

      4. change oil and oil filter

      5. adequate tire pressure (less tire pressure, more fuel consumption)

  274. TIPS:

    to avoid messing up with tuning your carburetor, just look at the carburetor of the brand new bike displayed on any motorcycle dealers and memorize & take note of the clearance and distance of the brass golden color needle from the top.

    apply this (what you see when you look at the brand new bike) while doing my latest tutorial in tuning the carb to the nearest default/factory settings.

    believe me, i had done all of these and loh, i’m successful. the bike runs fast and does not overheat. less fuel consumption. no more hiccups. one click on electric start and one kick on kick starter (without opening or moving the throttle) and the engine runs smoothly and automatically without stalling, etc. Engine sound is stable and the throttle response is quick. a very overwhelming accomplishment to me! let us rejoice!

    to God be all the glory.


  275. I tried what you had said in the post and the bike looked fine for a few days.
    Of late I feel a drag in the bike, if you know what I mean..i am forced to down shift too often for the bike to pick-up. The bike looks like its affected by Tb and is choking to death. 🙂

    The lower end pick up is linear, but as the speed crosses 80 the bike is looking helter-skelter for an Oxygen mask 🙁 vroooom….kkgh..kkough..kaputt!!! That is how it goes. All the way till 80 and then looks like it has lost all its energy.

    I ride a karizma-r and have easily hit 130kmph on the sam roads which I avoid now cuz am ashamed that the kids on bicycle may overtake. please help!!!

  276. @ afeef & vignesh

    my tutorial is specifically for tuning the carb of Yamaha SZ-R/SZ16 & FZ16/FZ-S motorcycles only.

    i don’t know exactly if the tutorial is applicable for Honda, Kawasaki and other various motorcycles.

    better ask your mechanic about it and let him reset the carb to default/factory settings. take note how he do it so you can do it yourself. don’t hesitate to ask questions to your mechanic.


  277. I have an old hero honda CD100 SS motorbike in good condition but I want to add self start engine technique into my bike as to add another one more option to start my bike. My question is that is it possible or not? If possible then how can I do it or get it done by others? how much it will cost in actual?

    I want an exact and realistic solution of my question and expert opinion in this regard. Kindly share it with me at earliest.

    Subodh Kumar Gupta
    Samastipur (Bihar)

  278. I own Suzuki slingshot plus bike. I heard that it has the most refined engine in this category. But I don’t think so. Because My Bike vibrates in even 45-50 kmph. This vibration is very noticeable while the engine becomes warm . Please help me. How could I solve the problem .. Thanks in advance. Email

  279. My bike is super splendor 2013 model .When I drive fast there is no problem but when I down the throttle at 40 km and when I start it smoothly again I feeling it my bike is missing.plz tell me the right tuning of carburetor.
    Thanks&regard deepak singh

  280. After following my own resetter tutorial for Yamaha SZ-R/SZ16 & FZ16/FZ-S, I noticed and observed that the fuel consumption lessens and performance improves compared to my first tutorial. my full tank of premium gasoline last up to 3 weeks (normal and daily use – city driving and long distance driving). my tutorial is successful.


    1. first tutorial = not successful, consumes more gasoline

    2. resetter tutorial = very successful, consumes less gasoline and runs fast (115 kilometers per hour maximum, almost full throttle)


    1. City Driving – 40 kilometers per liter because of traffic, frequent stops, etc. (60-80 kph on odometer)

    2. Long Distance Driving – 42 kilometers per liter (60-80 kph on odometer)
    – 39-40 kilometers per liter (80-100 kph on odometer)

    * based on many tests and calculations using premium gasoline. however, results may vary depending on the driving style and habit, weight of the driver, weather and road condition, aerodynamics, sprocket combination, motorcycle tune-up and maintenance, etc.

    • you’re welcome Imraan. 😀

      let us not forget to give a million thanks to the great contributors/tutors: Ashwini Kumar of and Srinivasan L of for their contributions and tutorials on tuning carburetors. without them i cannot complete my own way of tuning.

      my forever thanks to them. 😀

  281. Hi Ashwini,

    Thanks for your post. I have a pulsar 150 which has clocked 80k..i experienced a fall in the mileage and the pick up. Got it re-bored and the pick up is fine now. However, my mechanic told me I will have to run the bike for at least 500kms before he retunes it for good fuel efficiency. After the rebore the bike has run around 100kms and the mileage has dropped drastically (30 kmpl). Does the mileage reduce after rebore. If yes will it come up again after retuning?

    FYI : following parts have been changed
    1) Piston Assembly
    2) Oil seals
    3) Carb diaphragm
    4) Engine Valves
    5) Clutch Assembly
    6) All engine seals
    7) Spar plugs
    8) Cylinder bored

  282. Hi,

    I have honda activa bike ,i noticed fall in mileage after second service, it came down from 45 to around 40, i went to local mechanic , he checked the bike and tuned it.

    now i have observed one problem , when i slow down bike engine suddenly stops and when i start by button it takes some time. also i have not experienced increse in mileage.

    my question is whether he has increased the mileage or decreased.

  283. the setting is not optimal and i think mileage is decreased. you can follow my way of tuning by looking on the previous posts. you can do it yourself but be sure that you have complete tools and knowledge to perform it. it is better to research first and have a friend/buddy (who is experienced and knowledgeable) to assist/help you in performing the carb tuning.

    try to see these videos on, maybe these could help you. simply click the link to view.


    good luck bro. 😀

  284. When I limit a gear or try to my 250cc big boy loses power or when I pick up speed over 80km/h and the frotle is not compleet lee open it hickups or when i get to about 100km/h it does the same ..we had to replace the pusten and before that I could get around 130 140 km/h and I could limit each gear please help me and give me advice the mecanics told us timing and we set it right by their hulp … please help my she was always a dream to ride but she is giving me trouble i dont know what to do

  285. Hi ashwin,

    How can i do it in my passion pro as there is no rpm meter in passion pro.

    Please reply.


  286. Hi, Ashvini,

    It worked very well… My Honda CB Unicorn rocks now. Best tuning I ever had on my bike.It feels awesome. Thanks for giving me such a valuable knowledge. Thank u very much

  287. Hi Ashwini (actually Hi to all)
    I have a Honda Cb Twister 2014 model (i bought it 2 months back).i have completed 1100+ Km with first service completed .initially my bike had a mileage of 40 Km/litre and everything was fine .when i took my bike for its first service the mechanic did the regular oiling in engine(with a booster or something) nad i told him abt my mileage ..he adjusted the carburetor and my bike started giving me a mileage of 45-46 kmpl and the pickup was as it is.
    Few days back i again went to him for mileage problem as it has reduced to 38 kmpl..he again said (booster dal deta hu).and again tuned my carburetor ……no doubt mileage incresed to 50kmpl but pickup is just awfull..and i am facing the following problems:
    1.Bike stops anytime anywhere (does’nt starts with a self >>need to use kick).
    2.As soon as bike is started it turns off.
    3.above 40kmph it appears like my bike is about die and gives a lot of hiccups .
    4.engine oil is leaking .

    And following are my queries:
    1.Is filling engine with more oil is a bad thing for it (is it the cause of oil leaking).
    2.he turned the golden screw (must be fuel screw) anticlockwise which means rich mixture but still i bike was crying.
    3.twister dows’nt have a tachometer how will i adjust the carburetor with respect to rpms.

  288. Thanks for your fine tip,

    i have honda unucorn bike 2005 model.
    i am facing problem of smoking of engine.
    for that i was spent more than 10000 rs since last two year. i had change piston, valve and piston rings (3 times) but still problem not solved.
    milage and bike pick up is now tooo much wrost. .
    so please advise.

  289. I have a Fazer and the carb is Mikuni. When I increased the rpm to 3000 and started screwing the air fuel screw, the engine rpm doesn’t decreases. Nothing happened to the rpm when i fully screwed the screw and made the fuel the lineast. My bike was running as same in this setting.
    Please help me with this problem and tell me if the Mikuni carb has this problem or not.
    The same setting I had done on my CBZ extreme and was successfull bit not on Yamaha Fazer.

  290. Hello every one…..its really a nice post for everyone to tune their carb…i did my best with the tuning but i have a question on my mind…while tuning it for the rich mix, the rpm rises from 3k to 4k rpm what does this mean….is it more to the richer side or its just normal rich mix… article u mentioned if its more on richer side the engine rpm decrease but in my case its increasing… what can i assume….is it normal or more of an richer side.

  291. This is completly USELESS if you dont give atleast photo’s when you are explaining.

    What about people who dont know anything. Think practicle dude. Even I can write an Essay…but Photos are important.

    Anyways nice information and tech details even it has no use

  292. Hi,

    Please take some time read and reply me.

    My bike bajaj discover 125 is giving max mileage of 50kmpl.
    Its 2 year old ran 5,000km did 3+2 servicing.
    During its first 500km i had to run it on top speed long due to an emergency.
    On a recent servicing with oil changed, it gives black smoke and mileage 50kmpl.
    Now i tried tuning but hardly i could add a couple of kilometers more.

    This cannot be my rest point, please let me know what else i need to do.
    Do i also need to change part carborator or bore or bike whole.

  293. i have hero honda splendour pro. my bike gives 40 km mentioned in the article rpm meter is needed to tune carboretter …
    my bike doesnt have rpm meter how can i check rpm reading

  294. Hi, I have 200cc chinese enduro with KAIHIN EZ30 carburetor. I do have problem to locate those adjusting screws. Seems to me there is only one bronze screw with spring for adjustement. Can you please tell me, where those screws are located on this carburetor?

    Thanks JM

  295. Great article. However I beg to differ on the point where you say that the engine can overheat because of a rich mixture because when it comes to fuel-air mixture only a lean mixture (less fuel + more air) will cause engine overheating.

  296. Dear Ashwini Kumar,
    Thanks for such a clearly described instruction set.
    I have always watched my neighbouring vintage car mechanic do the same thing wondering the science of it all.
    I would always get him to tune my Activa carburettor after my service fellow had finished.
    His settings were always consistently good. He is uneducated but streetsmart.

    Only difference was that he would ask me to let my Activa cool overnight and i had to push it to his garage. (I was not supposed to ride it)
    He wanted a cold engine.
    He would turn up the idle screw and ask me to kickstart (not self start) and adjust the fuel screw provisionally to a point that the engine started easily without use of the Choke.
    Then as the the engine settled into a smooth rhythm he would fine tune about 1/8th turn either way with a hand on the handlebar to detect changes in vibration.
    Lastly he would reduce the idling speed to finish.

  297. hey, very nice explanation. I own fazer 2014 model. It is performing well and giving mileage of 41-45kmpl. But on my trip to shimla, it0 just halt on steep slopes. I am planning to go to ladakh on fazer with my wife as a pillion and this “haulting on steep slope” is haunting me. So, i wanted to know that tuning by your method will increase mileage or power. As i am happy with mileage, but concerned for power in higher altitude. Please do comment buddy.

    • Tuning your engine with the given method will increase mileage for sure and not power. To get more power, you need to set it to richer side. But I heard that for Leh rides, people tend to set Lean mixtures to let more air in. Better consult an expert who did Leh rides on Fazer.

  298. hi there.
    quick question.
    i have a 2010 honda cb twister with about 13000 km
    mileage was terrible. about 40 kmpl.
    tuned it like mentioned here. mileage increased to about 50 kmpl. bike response was awesome though. felt great.
    my problem is that in winter in delhi, the engine gets very cold. i need the bike only for 4km in the morning and 4 in the evening. so my problem is that the engine doesnt get to heat up too much during the trip at all. engine stops or stutters when i downshift to take the first few turns on every trip.
    is there a better tuning for the bike for short trips in the cold?
    also what else could be wrong for my mileage to be so low compared to other twisters.

  299. Hi Ashwini
    1. My Passion Pro does not start quickly every morning.
    2. Bike pick up is poor above 40 kmph.
    3. Also engine sound is a bit more.
    Reason: I messed up with Air screw.
    Please decode these symptoms.

  300. Please share your feedback, thanks. I have a 98 model CD100 SS. It used to cross 70 kmph effortlessly and returned a mileage of 55 kmpl in normal drive. Off late the performance of the bike has dropped. I had the engine serviced but still see no improvement. The engine struggles to get past 40 kmph and the mileage is just around 40 kmpl. Just after 3000 kms after engine service, I have again opened the engine and replaced the casing & bore along with other miscellaneous parts. It is 500 kms after this engine work now, and I see no improvement. I can only see that mechanics are eager to get older bikes for service only to make money as there are no authorised service centres now for old bikes. The engine still struggles to get past 40 kmph and cannot cross 50 kmph. The mileage is still around 40 kmpl only. Does this have anything to do with carburetor tuning/air filter/silencer/clutch plating.

  301. ashwini… sir i read your acticle… tried to do the same on my pulsar 200ns but im afraid i didnt got it right… the performance is not up to the mark plus i feel hiccups too and sometimes the rpm gets stuck at 2000 mark and den comes down to its original position which is 1500rpm…. can u plzzz tell me what should i do

  302. Nice and helpful article. I am facing a problem with my scooty pep plus. After running for around 6-7 KM as I brake to stop the scotter dies down, then I have to kick start it, it will fail to start with button. Please help

  303. Hi!!! I’m Arnab. I’ve TVS Apache RTR 160. Plz help me tune my carb for fuel efficiency. The last servicing has dropped the mileage to 15km/ltr.

  304. Hi,
    I have my karizma R.i left my bike for servicing. They had changed chain socket and timing control chains. But after servicing, mileage dropped 35 to 30 kmpl. If I change my air screw tuning, will I get the fuel efficiency as before… and also my air screw is jammed, how to take it out from carbirator.


  305. I have a Hero CBZ extreme sports which is 1 & half year old & has completed 21000 km, from last week its giving hikcups on 5th gear after its reaches 65 km/hr, it acts as it does not have fuel and have problem on only 5th gear
    I serviced th Bike cleaned the carburetor then too it has the same issue,
    please advise what needs to be done.

  306. Very good article, but how to tune If our bike doesn’t have an RPM meter. I own Bajaj Avenger 220 Cruise


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