O.S. Engine OS42581200 Carburettor Rotor — Replacement for RC Carburettor Assemblies 70R Fsa-155-P  [OS42581200]

Precision carburettor rotor for nitro RC engines

This O.S. Engine carburettor rotor is a direct-replacement rotary element that sits inside the carburettor slide assembly and helps manage airflow and throttle progression. It is engineered for the internal metering and rotational control needed during tune-ups and routine maintenance.

Fitting is straightforward for anyone experienced with nitro engine service: remove the carburettor, note the rotor orientation, inspect the slide and sealing faces for wear, refit the rotor onto its shaft with care, and confirm smooth travel across the throttle range. Work on a clean surface, use light force when assembling, and only reuse gaskets or O-rings if they remain serviceable.

During tuning sessions the rotor alters mechanical throttle behaviour rather than fuel chemistry; worn or damaged rotors can cause uneven idle or sluggish throttle response, so include this part in diagnostic checks. Clean gently and avoid harsh abrasives that could change fitment tolerances.