Does the pison have any scrapes and gouges anywhere on it? Are any of the rings broken? Do you seen any gouges in the cylinder? How about where the piston hooks on to the connecting rod? Does everyone look ok? How is the wrist pin and the wrist pin baring? If you found "debris" in your engine that sounds like a problem. Rubber sand? Whatever that is clean it all out. Also, did you lose a seal or something? Take the side plates off and have a look at them. Tell me, when you try to start it can you feel compression? I mean, when you release the clutch lever does it turn over and do you have compression?