RMX250 popped crankcase seal

in my last H/S hit a wall with  my RMX on the other side of a ditch. the bike stalled and was hard to start. once it started it would smoke and stutter and not pick up RPMs. needless to say the race was over for me. 

 

once I got it home, I found that the magneto magnet poles had come lose (the glue was probably old by now and the flywheel was rusty), when I replaced the left side crankcase seal, oil was coming out. when I checked the right side crankcase seal, I found that it had popped out of the seat all together and let most of the tranny oil into the crankcase. the seal looked intact, I will replace it with a new OEM seal anyway.

 

any ideas of why hitting a wall and stalling the motor would cause over pressure in the crank case and pop the crank case seal ? could the magneto failure have cause a glitch in the timing and cause a backfire into the crankcase to over pressure it and pop the seal ? I'm trying to understand the failure mode, so I can fix whatever caused it in the first place.

 

Backfiring would be the only thing I could think of that would cause that

well, it has been holding up after I put it all back together, so it must have been a freak incidence, probably caused by the lose magnets.

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