you have had either 1 of these happen to you -

Either the float is not cuting the fuel off AND you either left the petc0ck on PRI or the petc0ck is not cutting the gas off.

OR the petc0ck diapharm has failed and is allowing the fuel to run back up the vac line to the Carb and on into the engine - it leaks past the rings and runs into the crankcase - this is the most likely of two. Pull the petc0ck vac line and check it for fuel - should not be any- if it's bad fuel may just run out the vac line when you take it off.

fairly simple to plug the vac line at the carb and petc0ck - and either replace the petc0ck or convert it to manual

don't run it like this of it will fry the bearings and cam areas - might blow up for that matter - need to figureout which it is