40L 55Hz Carburetor Rotor for O.S. Engine OS25881200 Replacement Part  [OS25881200]

Replacement rotor for model glow engines

The O.S. Engine OS25881200 carburetor rotor is designed for RC carburettor assemblies that accept a 40L rotor bearing the 55Hz designation. As the rotating insert inside the carburettor it governs the air and fuel ratio across different throttle positions.

Used as a service replacement, this rotor helps bring back consistent throttle response when the original part shows wear or accumulation of deposits. The part form factor corresponds to small-model glow engine carburettors that accommodate removable 40L rotors marked 55Hz.

Fitting guidance: remove the worn rotor and install this replacement ensuring it turns freely and that any retaining hardware is refitted securely. Once installed, verify idle behaviour and adjust low and high needles as necessary to restore correct mixture and smooth idle performance.

Tuning note: the mating surface and clearance of the rotor influence throttle transition and idle smoothness. Correct fitment promotes repeatable needle settings and predictable throttle reaction during running or testing.