Iv had a unfixable problem jetting this bike since iv had it (excessivly rich/burning oil) which im sure is because of oil leaking into the crankcase now, back then it might of just been a seal, or maybe the case was already cracked some. I shouldnt have neglected to tear the topend off at least. Im sure i would of found at least cracks in the piston if not already some major damage and could have prevented the large hole in my case. My beleif is it is an oem piston. The previous owner was supposivly an old man but that didnt mean he didnt have a son who went and ran it WOT on a straightaway all the time or something. The topend isnt hard to tear off to inspect, and a wiseco piston kit is only 75$ and 20$ for a topend gasket kit, a new case will cost you at least 360$, and the time of splitting, disassembling, and reassembling with a new case is time consuming. If you have any concern about it, dont procrastinate like i did. Only wish i had knew about the oem pistons beforehand.