what is a "sport piston" ?

Ive heard people have cut some of the insides of the piston out and gotten a significant power boost!

any comments people?

Re: what is a "sport piston" ?

Why do people buy bigger jet carbs if they can just raise the needle??

Is there sometning else?

Re: what is a "sport piston" ?

Reall,Papa,you can't grind off weight from a piston without throwing it out of balance some with the crankshaft counterweight.Unless you'd weigh the piston first and then replace the weight some way.But maybe Fred will `weigh in' (Pun Intended) on this since he's into racing.

Re: what is a "sport piston" ?

..and here comes another one:

what is a high pressure cyl head??

Re: what is a "sport piston" ?

As far as raising the needle,there are no main jet needle adjustments on most `peds,so you replace main jet with different size.A high pressure cyl.head would be a head with a smaller combustion chamber and you usually are obliged to run PREMIUM grade gasoline or use octane booster if you install one.

Re: what is a "sport piston" ?

Ron Brown /


You can change the port timing of a 2 cycle by trimming the piston skirt at the port openings in the cylinder. This is usually don to increase power at higher rpm. Not usually a good idea for a ped as you loose too much low end and have no gears. You also need to know what you are doing.

A main jet controlls full throttle running when the needle is all the way out of the jet or at least is providing a larger aperture. Needle settings control 1/2 to 2/3 throttle openings.

Don is right on the high compression head except that you can raise compression some to improve low end without using premium gas.


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