Long story short. Bought a seized up GL1200 from a buddy. Tore it down found cracked #1 cyl bent valves. Got a hold of new used lower case, pistons and head. Rebuilt motor, by the way, hard to find new parts. Set the timing ran great for about an hour then started to get valve tap on left side then locked up. Pulled timing cover and left side belt was stripped about 4 inches and bent an exhaust valve. Not sure what could have caused this. Any ideas before I fix head and set timing again?