OK a friend of mine had this issue with his oem piston at I think it was about 27 hrs on the piston. Any ideas how thus could have happened? A little background the bike was stock except fmf exhaust and a Ron Hamp port job and valves. We think we know what may have caused it but looking for others ideas.
Yes that is the chunk from the piston that I found when I replaced his tranny gears to the updated gears, almost in the tranny area