# Two piston or 4 piston engine

1. Dec 22, 2009

### otomanb

suppose a bike which has 2 piston engine and other is 4 piston. which one is most powerful?
thanks

2. Dec 22, 2009

### mgb_phys

Depends on the capacity of the cylinders - you can build high power 2 cylinders and low power 4 cylinders.

Other than that it's a design decision.
2 cylinders are smaller and simpler, 4 cylinders allows a smaller capacity/cylinder so they can move faster and so rev higher.

3. Dec 22, 2009

### brewnog

Bikes painted red are always faster than bikes painted yellow.

4. Dec 22, 2009

### mgb_phys

Unless the yellow ones have noisier exhausts

5. Dec 23, 2009

### otomanb

Code (Text):
Bikes painted red are always faster than bikes painted yellow.
what is the reason behind that?

let me explain in different manner,
A bike of 100CC with 4 stroke engine
a bike of 100 cc with 2 stroke engine

Now which will be more powerful and fast

6. Dec 23, 2009

### xxChrisxx

The one where the driver only ate half his burger for lunch.

It's a totally pointless question, as it relies on so much more than how many cylinders it has. Tuning, gearing, size, weight etc etc etc.

7. Dec 23, 2009

### brewnog

Indeed, there are far many more variables than number of cylinders and capacity, making yours an impossible question to answer (hence my comment about colour). If you have a quick look round here there are some excellent posts on all the things which go in to engine power output and vehicle speed.

8. Dec 24, 2009

### Lsos

2 stroke engines are generally more powerful than 4 stroke engines...

9. Dec 24, 2009

### xxChrisxx

Oh, I really fail. I'm sorry OP you changed and clarifired the question, but I just read it as 2 cylinder 100cc not 2 stroke.

2 strokes are more powerful becuase each cylinder fires every crank revolution, as opposed to firing once every 720 deg in a 4 stroke. EDIT: In general.

Last edited: Dec 24, 2009
10. Dec 24, 2009

### brewnog

But it's a generalisation, there are plenty of four stroke engines more powerful than two strokes of the same capacity.