Torque the word itself suggest power from core. Earlier we had large number of two stroke engines in Indian market. These engines were known for it’s true nature – Power. Well let’s not talk about details about it’s Engineering. Lets talk about some of the spare which was helping to increase the engine torque.

Reed Valve, the main spare of two stroke engine which was contributing it’s help to increase the torque. This spare was also known as a NRV (Non-Return Valve), which was closing the door of intake manifold from inner side when piston used to start towards BTDC. That means keeping the charged Air/Fuel Mixture in the crank and pressurised it. Now in this case torque used to get high due to perfect quantity of AF (Air/Fuel) mixture.


Lets merge the same with four stroke engine now. In four stroke engine if you notice when piston about to come TDC position the Internal AF tries to back out from the same inlet valve, due to that the charge mixture comes back out from carburetor venturi, which causes black spots on the carburetor and lack of fuel to burn, that means lack of torque. So here mixing and merging some spares from two stroke engine to four stroke engine, in simple language putting Reed Valve on four stroke engine.

As per my experience when I did this engineering I found the bike stopped backfiring, back kicking, smell of fuel and good power. I used the same concept of Reed Valve. After some engineering I did put on reed valve when piston used to travel from BTDC to TDC the Reed Valve gets closed and keeps the charge AF in the chamber due to that I found great change in power.

Though the fixing of the carburetor with reed valve was temporarily, it was just for testing purpose. But the result was great. Basically, in two stroke engine reed valve acts when piston is coming towards BTDC, but here in four stroke engine it acts when the piston is coming to TDC position. When piston comes from BTDC to TDC in that case Valve never get fully closed so due to that piston somehow reverse the main AF to inlet manifold or till the air filter. But after Reed Valve it stopped reversing the AF till Carburetor. That means fully charged AF for burning and torque.

Chinmay Dangre

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  1. Balu: What about the mileage?

    I am pretty sure that it would affect the mileage, but those who are ready to get a better performance from their current motorcycles wouldn’t care much about the mileage.

  2. Thanks Deepak.

    Well Balu, YES when we talk about High performance we can’t talk and think about AVG. If you want good mileage then reduce the carb venturi size from stock. For example if the stock carb is VM24 series for “RE” then reduce it. IT should be lower than 24. Many people come to my workshop with small carbs for better avg. But in that case the top speed becomes maximum 60 – 70 app. So when you want mileage you will fail to get top speed and when you want top speed you will get low mileage.

  3. Hye chinmay… You’ve spotted out one of the minute things which would actually bring about a drastic change in the combustion process. You’re good. I can say this coz i myself am an automobile engineer. … But one Asshole in Apache community thinks this is bullshit… He has zero knowledge bout bikes and other vehicles but has good vocabulary of slangs. He’s talking bout inlet valve only coz i think its the only thing he knows 😉

    I just wanted to appreciate you bro… Good work. Keep it up.

    • i agree with you kandy instead of this we can reduce the sprocket size or install high lifting cam shafts with K&N air filters and iridium spark plugs to our bikes for increasing the torque.chinmay’s idea sounds stupid to me in some cases the compression ratio can be affected due to the reed valva in long run>…………………

  4. Faisal,
    Reeds where used only for 2 stroke engines. Since I did some arrangments and tried to use the same on enfield engine. So u can’t find any reed which is for FZ. Right now I am working on proper reed for Bulls.

  5. dude,
    i’ve been googling for so long for this kind of mod until my friend appointed me this site..this idea came across my mind sometimes back..good job there..but i think it would more efficient if you could shorten the intake manifold…just a thought tho..

  6. @ iwae405,
    Tx for appreciation. Well there were some techincal issue while making the intake manifold. Plus I wanted to attach supercharger. So the arrangment was by considering some of the points for engineering purpose. Your tought is right about small intake. Well I wanted to make a small intake but the reed was too big and the carb was from CI500 so had to do lot of in simple way, the main reason behind all this structure was to make it in less amount. Well I am trying to make the same with small intake with bigger carb. But offcourse this time I am sure I will make it with supercharger..

  7. i am trying to put a turbo charger on my bull electra…i tried and found the worlds smallest and efficient turbo which is from 500cc-660cc engines….i am hoping that it will work on my bullet….can i get some knowledge from you about this…my email is do mail me ok…nd good article bro..

  8. Dear Gary,
    If i am not mistaking then u have got RHB21 series smallest turbo which is for 500cc to 600cc.
    I would like to know more from you. coz some of the turbo need oil and coolant line so if u have that kind of a turbo then…..anyways more info we will share through mail.
    my mail id is

  9. dear chinmey,

    today it is the first time i m reading your articles and benefited a lot. i m also a mech engineer and currently working in a TOYOTA dealership in Punjab.Man u have had a great knowledge about automobiles.even i m also designing one fuel intake system for four stroke bikes.i m currently almost at last stage.When ever i will need any help surely consult you.

    one thing more as the Gary (person in the mail)had taken the responsibility of attaching turbo charger with the bike, lot of things should be put into consideration like:
    1.Turbo chargers which are meant to solve the purpose on petrol engine are not exhaust turbo chargers, the fuel charger used to solve the purpose is SUPERCHARGER, it works via crank shaft not by exhaust manifold as in petrol engines the exhaust is not so powerful that could be used to inject sufficient air needed for charging the fuel.
    2.The use of Supercharger should also be accompanied by Direct or Indirect Petrol Injectors not with carburetors as this will make the mixture very lean and finally the engine stalls.if you don’t believe just try it.

    (I had worked on it from last three years and got the answer to the problem, But you have to wait till i get it patented.)

    good luck for near future,keep on writing.



  10. Hi Chinmay, I am new member to this Blog. i find it very interesting and it had helped me a lot on performing couple of mods on the bikes. I work with an US IT Firm but my weekend hobbies are bikes. I have 2 queries as of now.
    1. I recently installed a K&N on Yamaha FZ16, Have done the up-jetting but my concern was about the Crank breather and emission converter, i have connected these 2 hoses to the stock air filter and have sealed the main vaccum pipe. K&N is installed directly on the CARB. Bike’s performance seems to ahve changed a bit (good) but would it harm the engine if those 2 hoses are fitted to stock air filter?

    2. What is a induction system, on what circumstances, it can used on a bike.

  11. Hi chinmay, you doing a great job yaar.. You proving and expanding your talent by sharing your knowledge. . I am too crazy about bike modification and even i carry out altertions like porting etc. Now at present i am facing problem in choosing a reed valve in carburetor in yamaha rx 100 bike to increase torque: wil you help me out yaar:)? i hope you wil help me seeing your talent. . . .

  12. Excusite work done sir. I have Yamaha R15 motorcycles & would like to know if there is a possibility to fit a turbo in this byke & whether this type of turbo available or not.

  13. Dear Friends, Chinmay/Prakash and Vivek. I have some knowledge about working of two and four stroke engines. I am very happy that without a proper support you guys are taking so much of modifications yourself. I wish u all the success in your endeavor.

  14. Dude, a 2 stoke engine has a reed valve to stop the blow back from the engine since it does not have a inlet valve for the purpose. In a 4 stoke, the inlet valve is closed during the compression and the power stoke, therefore there would be no blow back at all. I repeat, a 4 stoke does not need a reed valve since it serves no purpose, the inlet valve is already serving the very same purpose. But still i appreciate what you’re doing, since i learnt things the hard way too when i had an Rd350. Now i moved on to bombing diesel motors. the best way to learn is like this, by trail and error . Take care

  15. Also, torque can be called as the pulling power of a vehicle. Its the direct power output calculation of the engine. Horsepower on the other hand is not a direst power figure, its the secondary figure calculated after the torque figures in the entire rpm range of the engine. In other words, its a calculation of how much torque the engine can push within the rpm range. Therefore the max hp of an engine would be at the rpm when the torque starts to fall of vis-a-vis the rpm, like for instance, Horsepower=Torque (in pound per square foot) x rpm / 5252 (unit figure) . Therefore, the higher rpms the engine can utilize its torque at, the higher its horse power would be. Take this as an example, a Tata 1613 truck with the 5900cc turbo-charged Cummins engine makes around 127 hp, whereas a Tata Safari with a 2200cc Turbo makes 145hp. Does that mean the Safari has more power? or Will it be able to pull a heavier load than the truck?
    The answer is no, and thats because the Tata truck, even with just 127 horses, has 42kgm’s of torque, which is way more than 30 odd kgm’s of torque the Safari produces. Now if it has more torque, why does the Truck still make less horsepower than the Safari? Well thats because the Safari engine is tuned to push more torque at higher rpms, and the truck engine is designed to push max torque right off the idle speed of the engine (infact, thats the reason why the Mahindra Scorpio has less hp than the Safari, even though they have the same capacity engines making roughly the same amounts of torque. The torque in the Scorpio is delivered earlier and diminishes earlier too, resulting in more pulling power in lower rpms than the Safari motor can produce, while the Safari has more pulling power in higher rpms). Infact, the truck engine is governored at 2500rpm, and just by changing the governor spring in the fuel pump to a longer spring that governors at 3200rpm, you can get the same engine with the same amount to torque (though now made at a higher rpm than before) to make 160hp, without even touching anything else.

  16. nice article.
    very few can think at this level.
    as an automobile enthusiast i wonder y can’t we make a cheaper fi systems rather than fidlling still with carburetors for bikes( all cars use fi for emissions).
    i will be pleased if u can mention the price diffeernce between fi system and carburetor system.
    can’t the price come down if mass produced?
    i think back flow occurs as inlet valve is not completely closed(due to cam design(egg like)).

  17. I have purchased a Dio & i want to modify it, specially make changes in the engine & i am planning to change the filter, which one would be the best for my moped?

  18. I want to know about the torque of at different gear.In bike technical specification they only mentioned max torque.Can you please help me in this issue?

  19. thanks…. dis one s a great idea and along with dis, reed valves are used for correct distribution of fuel into the bore and save fuel with dis reed valve . den how could u say tat der s lack of mileage ? please explain me abt dis?


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