About 10 years ago I was riding my sportbike at a track day. A very nice guy we knew was there supermoto'ing his dual purpose YZ426 (harescramble and supermoto).
A buddy and I caught up with him to chat in the pits, and it turns out his motor popped out on the track the session prior. I've never seen anything like that -- we counted five separate holes in the motor. If I remember right - two in the cases, front and rear of cylinder, and something came through the head or valvecover. We felt bad...