That can't be right, Scuba. On my TKR2, the air cooling fan screws onto the magneto flywheel, and if you were right it would blow fuel/air mix all over the place. The crank on the TKR2 is stepped and the outer lesser diameter part drives the air pump. There's a minimal hole at the front, where the stepped down part of the crank drives the air pump, but that must be air tight otherwise fuel mixture would leak into the magneto housing and get blown about into the cooling ductwork by the air fan on the flywheel. The crank seal is outboard of the hole (slightly) but as the crank is solid faced, it must provide an airtight seal.
