Your timing chain must be a little claustrophobic, Vedran, and was desperately seeking for open space :-D. I wish nothing worse happened inside, though.
It seems so When something like this happens does it have as a consequence bent pushrods, valves etc? I didn't had time to inspect the details since I was in a hurry to put replacement engine. The new engine fired as soon as the fuel reached the carburretor and everything was fine but then I've noticed that the fuel pump is substantially leaking fuel.
It should be ok on our little engines, if there is any valve/piston contact it's normally the pushrods that would get bent, I had an old Transit that snapped its cambelt and we swapped the pushrods, changed the belt and had it back on the road in just under an hour!