I found that engine to be a very beautiful example of pure talent. I noticed the wobble of the crankshaft, perhaps they used a replaceable stud in the crankshaft in the event of a crash? Perhaps that got bent from tightening the prop down?

It almost looked like the crankcase was cast, but I couldn't tell without having an HD playback. Either way, its a very beautiful engine. Sounds great. I'd take the prop off and put a flywheel on it and run it on a Go-Kart.