Is that grooves in the cylinder? Hard to tell from pic.. piston rock from incorrect piston to cylinder wall clearance would be my guess... and it is a guess... Did it knock when running?
The ring gap would say that might be the case too though..
'06 TRX450ER, '03 XR400r, '04 CRF450r, '05 CRF250r, '06 CBR1000RR (StreetFighter), 07 GSX-R750, '71 CB500, '75 CL360 (Honda Scrambler), '81 Virago XV750 (the 110 Bike).
06 Black TRX450ER (Conv to kicker) "Medium" Big bore! Quikshrk (OCP), Demon, REAZ bits.
Last edited by OTMTRX; 02-15-2013 at 08:43 PM.