This is not a common thing, sounds to me like someone had a major piston failure , fixed the piston problem but failed to check the crank. The damage probably happened the first time the motor was refired. Cases can be welded , and the crank should be fixable as for the flywheel , it should be ok but it probably took out the coils on the stator, you can get new coils for the stator plate. If you can't the parts you need on that side of the pond let me know and I will see what I can do to help. CBX
was thinking it might be piston failure but the barrel and head are in good condition except for a small chip on top of main exhaust,the piston had a big piece of skirt missing on exhaust side and someone had filed it and reassembled,
my other though was that some forced the crankcases together when assembley [but the bigend conrod looks worn]
donnt think the motor would run long with the crank that bent
look like some could have changed the coils and left the flywheel
at first i tought it was someone gettng heavy handed removing the fly wheel until i realised the clutch side was also bent
as for welding cases i think the the crankshaft bearing housing are worn [play in -out and no up down play]
this is the third set of cases i have with worn crankshaft bearing housing[