Pistion ?

[rider250ex]

hey. i knwo this is a really dumb question. but i blew my top end the other day and i was wondering if anyone could help me with what bore its on. the guy i bought it from said he doesnt know. its a wiseco prolite piston and the number on top is 526mo6725 and i was wondering if that meant it was 67.25mm or if anyone knew what it meant. thanks

[ZRider400]

measure the piston.... if your not sure about the numbers.


and measure the bore.

[xlr810]

The number you listed is for a 67.25mm piston. It is the earlier (85-86) style.

[ESR350r]

You are right, the size is 67.25, you have 2 piston sizes left. I had an an 86 R that had that piston in it till i got a ESR bigbore. You can order the next size which is 526mo6750 for 121.99. Good luck man.