Anyone know what the stock measurements are on 76 piston? I'm trying to figure out what size bore pison was in my bike and I can't find any documentation that says what the stock measurement of the piston was. Well let me rephrase I did find something on jpcycles that looks like it says stock was 3 and 3/16". Also it might be helpful if someone could post what the size of the piston would be if it bored over the following:

20
30
40
50
60



I bought this bike a few months ago and have started a top end rebuild because it was burning oil, but I don't recall what size it was and I am needing to buy new rings so this information would be really handy to have! LOL

Thanks guys!

 

Std: 3" 3/16 = 3.1875

+20thou = 3.2055

Etc...

Patrick

 

Spectacular. Thank you very much. Now I will know what size rings to order! Thanks again.

Edit: Okay so I measured with my caliper and I get 3.196 ~ 3.198. So by using your math that would put me at a bored 10 over right? The piston measurements aren't making much sense since I am getting around 3.178 which is below stock size. I believe that is just crappy angle I am having to measure at. Would you all agree with the fact that I would need +.10 rings then? Or should just be safe and go with +.20 over?

 

The piston will also have the size stamped on the top if it is an overbore piston. For instance if it has been bored before you got it to .020 over then the piston will have +.020 stamped into the piston.
Be sure to measure the bottom of the bore (where the rings don't travel) using an ID micrometer if you want to see what the actual bore is. The top of the bore will be worn.......pg

 

Keep in mind that new pistons can vary +-.003".....I recall a set of brand new .020" over pistons for a 900 which has a stock bore of 3.000" actually measured out at 3.017". Like pinion said, look on the dome of the piston for numbers. If you see STD that means Standard size.