Short pistons - more HP???

H

hugabuga

New Member
Hey my name is Yuval.
I am rebuilding a cb360 and a friend of mine told me that I can get a shorter pistons to my engine and it will give more power to the engine.
He said that the original cc amount of the engine will grow up because there is more space in the cylinder.

Is it real? anybody ever try it before?
If yes , what are the additional changes I will need to do to make it work?
Does the engine are strong for a change like that?
 
if you get shorter pistons, there is going to be more space (less compression) when the spark goes off, giving you less power
 
Re: Re: Short pistons - more HP???

raptormeat said:
if you get shorter pistons, there is going to be more space (less compression) when the spark goes off, giving you less power
Click to expand...

Thank you.
I wont do it.


Sent from my GT-I9100 using Tapatalk 2
 
There's really so much more to it than all this... Do some online research to start, and find a proper mechanic near you.
 
Now that we've made fun of you a little, here is a simple answer to your question.

The key is what's called "displacement." Displacement is a function of the bore and stroke of the engine. Changing the length of the piston does not change either the bore or the stroke.
 
Assuming that the guy isn't a complete moron, maybe he means shorter pistons=lighter pistons (less/trimmed skirt)=equals less rotating mass=faster revs. That's the only way I can make sense of that.
 
That was my first impression from the thread title, but after reading the first post, I realized that someone was trying to tell him that if the piston crown doesn't go up as far in the bore, it makes it a bigger engine.

I suspect that the original poster does not have English as his first language, so his wording is a little unusual.
 
Re: Re: Short pistons - more HP???

AlphaDogChoppers said:
That was my first impression from the thread title, but after reading the first post, I realized that someone was trying to tell him that if the piston crown doesn't go up as far in the bore, it makes it a bigger engine.

I suspect that the original poster does not have English as his first language, so his wording is a little unusual.
Click to expand...

This is true.
Im from Israel and this is my English.
I think that you can understand me well

Sent from my GT-I9100 using Tapatalk 2
 
hugabuga said:
Hey my name is Yuval.
I am rebuilding a cb360 and a friend of mine told me that I can get a shorter pistons to my engine and it will give more power to the engine.
He said that the original cc amount of the engine will grow up because there is more space in the cylinder.

Is it real? anybody ever try it before?
If yes , what are the additional changes I will need to do to make it work?
Does the engine are strong for a change like that?
Click to expand...

No it isn't real, your friend is an idiot
The only wat to get more power is either rev higher or increase displacement.
Easy way to increase displacement is bore 2mm oversize and fit Suzuki GS850 pistons
 
o1marc said:
If I do understand your English I would advise to quit listening to your friend. ;)
Click to expand...

His friend is probably talking about shortening the intake skirt on a piston ported two stroke but has no clue on the difference between a 2 vs 4 stroke.

Or something is being lost in translation, either between friends or by the op on here
 
He might be thinking of the stroker kits you can get for some dirt bikes (longer rod, lower deck height piston) and thought you could buy off the shelf kits for other bikes too.

Either that or he's just not too bright.
 
crazypj said:
No it isn't real, your friend is an idiot
The only wat to get more power is either rev higher or increase displacement.
Click to expand...

Lets see who else is an idiot. If you do not change the size of an engine or the rpm you are measuring horsepower at but can increase it's volumetric efficiency at that rpm you will get an increase in power without either raising the rpm or increasing it's size.

Now go sit back and pour yourself a big cup of Duh.........
 
Sorry, the intake on CB360 is already too big and exhaust marginal.
As the guy knows nothing about engines I really don't think it would be a good idea to confuse him even more talking about volumetric efficiency and, what basically amounts to porting a head
The easiest way to get more power out of a CB360 is bore it and rev it higher, I know, I've done several
The exhaust port needs a little work but if you don't know what to do you'll make things worse not better
 
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