I've posted this on a cbr forum that I also use but I trust the answers coming from this forum more so I'm also posting here. So I had a valve collet or valve keeper get loose allowing the valve to sit and hit the piston a few times. So I tore the head off and see that the piston is slightly damaged from this valve and I'm wondering if its still usable. There are little bubbles as you will see in the pic but mine has been shaven down slightly from the valve and the other circled part is where there is a little nick in the valve groove. Think I can sand that down and still use this piston? I would really rather not have to split the case if I can. Any insight welcome.
(http://i41.tinypic.com/30mu9a0.jpg)
Well it's less than optimal, but I don't see any evidence of any damage to this piston that would make it unreliable. I'd be worried about the valve, but you didn't ask about that.
Justin
Yeah I've come to terms with the valve being bad so I ordered a new one, the bike ran for less than 5 minutes with the valve floating there (shim under bucket ordeal, dohc) so I'm hoping the guide is ok but I'll take it to a machine shop and have them check it. If its of any value this is on a track bike so it won't be run too much, I just don't feel like dealing with a new piston right now.