I finallt got the motor disassembeld on project TLR. Given the overall condition of the bike, I feared the worst. The good news is that the piston looks fine and the ring gap was not too bad.I plan to go ahead and re-ring while I have the chance. Bad news: the bottom of the sleeve of the cylinder. I found a small piece, about the size of two pencil erasers, broken away. I figure since it is at the bottom, I should be ok. It kind of looks like rust damage - an uneven edge. I would guess that it is maybe 6 or 7 mm square in size.
The combustion chamber sure needs some cleaning, that I will do when the valves are pulled for replacement. Top of piston looks pretty good. Cam chain guides show a lot of wear. I picked up replacements along with the cam chain. Anything else I should be looking for?