Purchased the bike seized. Tore it down. Piston broke and locked it up. New bottom end, replayed cylinder, new top end. While putting the top end on I had problems. Lubricated new piston and cylinder, tightened cylinder down. Turned motor by hand with flywheel weight. Everything felt good until the piston was at the bottom of the stroke. Something was in a bind and I could no longer turn it either way. Removed cylinder nuts and took pressure off the base gasket. I was then able to turn it again by hand but could hear metal to metal contact at the bottom of the stroke. Pulled it apart and I can't find any evidence of where the contact is happening. I believe the skirt on the bottom of the cylinder is contacting the crank on that portion of the stroke. Almost like the crank is not perfectly round. Any help or suggestions would be greatly appreciated. I was considering lightly coating everything with some grease to see where the contact is happening.
