FSa-72 Service Crankcase OS44301000 Replacement for FSa-72 by O.S. Engine  [OS44301000]

Crankcase function and service importance

This crankcase is an RC-scale replacement part produced by O.S. Engine for the FSa-72 family of model engines. It is the main structural component that houses the crankshaft and bearings, used during repairs, rebuilds, or as a field spare for engine service.

Compatibility is limited to the FSa-72 designation shown in the product name, so confirm the engine model before ordering. The crankcase maintains bearing alignment and supports connections to the cylinder and gearbox; ensuring accurate mating and clean assembly is critical to long-term bearing performance.

Installation notes: detach the engine, disassemble per the manufacturer's order, move bearings and small parts as necessary, and pay attention to end-play and rotating smoothness when reassembling. Prevent debris ingress and check threaded and machined surfaces for signs of wear.

Tuning and service role: while the crankcase does not alter tuning maps, an undamaged and correctly installed crankcase contributes to consistent crank timing and sealing, which helps the engine respond predictably to carburetor and exhaust changes.

Select this OS44301000 crankcase for like-for-like replacement when maintaining FSa-72 engines and follow recommended rebuild checks for dependable operation.