The crankshaft is supported by two bronze bushings. One is contained in the crankcase on the ratchet side of the engine. The other is in the main bearing housing on the magneto side of the engine. The bushing length is 1.75". The inside diameter of the housing opening for the bushing is 1.060". Most machinists recommend a bushing be about .001 larger than the matching opening. The ones pictured here are custom made bushings that provide the needed specifications. The bushing used on the magneto side uses an oil groove, but the bushing on the ratchet side does not require the oil groove.

Determine the current status of the crankshaft to crankcase fit. Make sure the parts are clean and free of rust, dirt, and grime. This main bearing housing has a gasket that measures about .020 thick. The end play on the crankshaft appears to be about .010 so a thinner gasket can likely be used upon final assembly.