Was it smoking at all out the exhaust? Cuz if you dont have any smoke i wouldnt change the piston or rings either. I just took mine apart and it looks pretty much like yours my cylander walls are smooth but deffinitly check the rod for up and down play mine moved like an inch up and down. Oh and another thing i know this isnt a common problem but make sure you check your oil pump because i put mine all the way back togeather and the oil pump failed causing my rod bearings to go that bad. So while your there check it. It will save you headaches down the road.