Finally got the puller tool I’d been needing to split the cases and take a look inside at exactly where the motor failure happened.
I got the flywheel off and proceeded to split the case. This gave me my first good look at the crankshaft, where I’d assumed the failure had started.
Pretty obvious something here got hot.
The rod is still completely frozen to the crank, so I assume these surfaces got hot enough to friction weld to each other. I wanted to tear down further, but another specialized tool is required to actually take the crankshaft out of the case. Unfortunately, amazon doesn’t stock specialty tools for 2 stroke vespas, so I’ll be waiting another couple of weeks before I can take everything apart fully. I really want to find the bearing that came apart and sent shrapnel into the top end.
FWIW, I already ordered a whole new engine assembly, so at this point I’m going to continue tearing this one down simply to satisfy my curiosity. Hard to argue with $650 shipped for a brand new motor.