O.S. Engine OS45561110 Rocker Arm for FS-120SIII and FT-300 Engines  [OS45561110]

FS-series rocker arm overview

This O.S. Engine rocker arm is a direct replacement for FS-120SIII and FT-300 engine types named in the product title. It transfers cam movement to the valve train and is supplied as a service spare for maintenance and repair of glow-powered RC models.

Compatibility is restricted to the engine codes listed, so confirm your engine designation before purchase. The part is sold as a single pcs unit intended to replace a worn or damaged rocker arm in the specified engine assemblies.

Fitting requires basic disassembly of the small engine and familiarity with tiny fasteners and bearings; apply appropriate thread lock and controlled torque during reassembly. After installation check valve clearance and timing to ensure consistent valve actuation and expected running performance during tuning.