I've personally pushed the motor up through the tank of a kawasaki 750 triple (two stroke 750) in the early 80's.
Interseting day, (not my bike). we did a whole loop the loop in the air and crunch and flip ,took a piece out my lower spine as we hit. Miracle I can still walk etc with no pain and no op, it has naturally fused itself.
That was it for me,other than a quick burst occasionally but what life without its risks