My bike jumped timing, and the piston contacted the valves. I got off very lucky though...bike stalled while on a nasty down hill, and I was going very slow. Hit the Estart and it made bad, bad sounds....lol....never tried it again after that. Took it apart and the timing was completely out to lunch, bent valves (intake took the worse), but no other damage! You can see where the valves "cleaned off" the carbon on top of piston, and some very, very minor contact impressions on piston itself once we cleaned it. I have to say, I'm pretty impressed with the Athena forged pistons in their big bore kits. So, I need valves, and get the seats redone, timing chain (Timing chain was the culprit btw...it was whipped...my bad). OEM valves, or SS valves? If SS Kibble White still the best going? I only trail ride...no racing, no track, etc.