Two Stroke Vs. Four Stroke Engines

Stroke refers to the movement of piston in the engine. 2 stroke engines make piston move twice and 4 stroke engines piston moves four times in all the directions. Each movement of the piston (stroke) is characterized by a unique activity of compression of fuel and generation of power. So what exactly is the difference between 2 and 4 stroke engines? Let us find out:

Piston moves only twice in a two stroke engine. The first movement is called the compression stroke and the second stroke is called the power stroke.

  1. Compression stroke: Compression stroke is an act of compressing fuel. During compression stroke piston goes up compressing the fuel in to the engine.
  2. Power stroke: Compression stroke is followed by power stroke. During a power stroke the fuel is ignited, which pushes the piston down producing a lot of power and torque. It also involves in taking new fuel and air to start compression again.

In a four stroke engine, the piston moves 4 times i.e. two sets of ups and downs. The movements are characterized as follows:

  1. Compression stroke: During this stroke fuel is compressed. The compressing is essential to generate power at the later stages.
  2. Power stroke: The fuel ignites and moves the piston down. The act of moving down produces power and torque.
  3. Exhaust Stroke: The piston again goes up and drives the power emitted and fuel out of the exhaust valve.
  4. Intake stroke: The piston again goes down and draws new amount of fuel and air ready to compress again.

Thus as you can notice that two stroke engines involves only two moves and 4 stroke moves 4 times.

Basic Features: As a 2 stroke engine receives power stroke twice than that of four stroke engines they generate more power and torque. Also, 2 stroke engines are noisier when compared to four stroke engines.

  • 2 stroke engines does all the act of exhausting and taking fuel in at a single stroke i.e. power stroke, it is more polluting.
  • 2 stroke engines want more lubrication when compared to four stroke engines. One will have to keep the engine lubricated frequently (oiling) for smooth riding experience.
  • 2 stroke engines are not suitable for long term as they tend to produce more noise and pollution simultaneously.
  • 4 stroke engines are fuel efficient, smoother riding experience, less polluting and least noisy.
  • 4 stroke engines do not emit as much smoke as 2 stroke ones do. They also have a long term life.

The Final Verdict: Though a two stroke engine emits more power and torque, they are not suited for the day to day activity. Moreover, they are not fuel efficient, have a short life, polluting agent and also noisier than 4 stroke ones. Therefore, 4 stoke engines should be preferred as they are more fuel efficient, less polluting, and affordable. 4 stroke bikes are ideal for day to day activities.