Piston help...

fish22 · Oct 14, 2009

have my motor apart to fix a shift fork and i was told that the motor had been bored but the guy i bought it from didnt know how much(not original owner) it had been bored out to.
Someone on here told me while fixing the gear to look at the piston and see what it said. that it would be stamped. But i dont have a clue what all these numbers mean, maybe you guys can tell me. The piston was stamped as follows:

C00A5
4419M08350
XC

DeadLastRacing · Oct 14, 2009

I know that XC is your ring thickness. Don't have a clue what the others are. Have any idea who manufactured the piston? If you you could contact them and they should be able to tell yah what the numbers mean.

Easiest way to tell would be, measure the cylinder walls or piston width with a digital reader.

fireworrior · Oct 14, 2009

I belive thats a Wiseco piston 4419 part number and the 8350 is actuly 83.50mm 1st overbore!!! So it's .020 (.50mm) over.... Wiseco pistons go up to 84mm which is 1.0mm overbore, just before the 85mm overbore limit. I have the same pistons 8350 and 8400 which is 83.5mm and 84mm over bore.
Check out wiseco piston's website for more info..

Hope that helps

fish22 · Oct 14, 2009

Thanks for the reply,
All those numbers kinda just go over my head.... lol
Is that good, bad, awesome, kinda neat? lol

I was told that this dude was building it to race but bent a shift fork ( freaked out and sold it)
I bought the bike for $500, and only had to place helicoil. and the 3rd shiftfork
FMF, K&N, bore to something, Carb(not edle),