I had some oil seeping at my left side cover on the 70 AT1. I pulled the armature and the crank seal was popped out from the crankcase. I've seen them bad (torn) but never popped out? Could it have shrunk from age or is there possibly something causing pressure in the crankcase?

I've had that with a G5 80cc. Think they just give up being tight after many years then crancase compression just pushes them out. But they can get blown out if the motor gets a belly full of fuel from flooding carb overnight, then first kick is toio much for the seal. Even ignition timing if the crank key is broken & it firing while transfers are open. New seal & she'll be good. If the other side pops out she'll smoke the village out--if it runs at all. My AT1 is on original seal so i guess it'll happen to me next haha. Mine is a magneto model not leky start.

Thanks for the info. I have a Yamaha seal on order.