O.S. Engine OS40981200 Carburetor Rotor for RC Carburettor Assemblies  [OS40981200]

Replacement carburetor rotor for RC engines

This rotor is a replacement part sized for RC carburettor assemblies and is designed to bring back consistent throttle response and correct mechanical fit inside compatible carburettor housings. It acts as the rotating throttle element that engages the carburettor body; if the rotor is worn or damaged it often produces uneven throttle feel and idle instability. Fitting a new rotor is a common maintenance task to restore smooth control.

Installation is a straightforward job for hobby technicians: remove the carburettor from the engine, note the rotor orientation plus any shims or retaining clips, clean the mating surfaces, and install the new rotor making sure axial play is minimal. Confirm the rotor moves freely through its travel without binding, then reassemble and verify throttle return and idle before running.

During tuning and setup, a correctly fitting rotor reduces variables when adjusting needles and throttle progression. While the rotor does not tune mixture by itself, consistent rotor geometry helps technicians achieve repeatable needle settings and steadier idle behavior during troubleshooting.