I have a 1998 Polaris Xpress 300

I took the piston and cylinder into the shop today to see what exactly needed to be done to the cylinder as far as honing and boring it.

The guy at the shop measured the piston at 2.925
He told me to go with a piston the next size bigger then bring in the cylinder for him to bore it out.

Can someone help me out on how to go abouts getting the right size.
Also how exactly do you go about reading and purchacing piston sizes. I have the general idea, just need it explained better to me. THANK YOU

 

Figured it out-
My piston standard size is 74.50mm, 1mm=.039''
Need it bored to no more than 1mm over
So gona overbore it .010'' or .020'', probably go .020''

 

just got the .010 that way you dont use up a bore size. there are no real gains from boring these small motors

 

Go with the .020 over just to be safe.The stock bore lasted you 10 yrs if this rebuild last half that you still have up to .080 to bore out.

 

Kelly: I go with "egg" on this one - only go the minimum over that you need -- It sounds like you only have aluminum "deposits" on the cylinder, now if you have deep grooves in the cylinder wall, THEN you may have to go with a larger overbore. Your machinist should be able to accurately tell you what oversize you need and he also should know and allow for the proper piston to cylinder clearance for the type of piston you have. If he doesn't, I'd be going to a different shop.