Matching a piston to a cylinder

[phonce]

Hi , this is my first time posting on here , so here goes. I am working on a 1986 Moto 4 Yamaha 225cc. atv and was told the cylinder is not the original one. I need a piston for it but the damaged one seem to be sloppy in the cylinder. I think it was the wrong one for the machine. The cylinder measures 71.5mm. , can anyone tell me what size piston I would need for this. Would a 71mm. do the job?

[Dirtcrasher]

Although it isn't a trike, welcome to 3WW!!!!!!!!!!!!!! :D


.5MM is about .020 or twenty thousandths larger. 1MM is just a bit smaller than .040 or forty thousandths.

It's best to hand the cylinder to a shop and have them measure it up in a few places thru the bore. Then they can bore it .003/.004 over depending on what type of piston gets used.

But no, a 71MM piston would be 2 overbores (.010 each time) too small in a 71.5MM bore.