O.S. Engine OS25881200 Carburetor Rotor 40L 55Hz replacement carburettor part  [OS25881200]

Carburetor rotor for RC engines

This O.S. Engine OS25881200 carburetor rotor is an RC-scale carburettor component intended for use in carburetor assemblies that accept a 40L rotor with the 55Hz marking. It serves as the rotating element inside the carburettor body and plays a direct role in air–fuel metering at varying throttle positions.

Designed for replacement and routine maintenance, the rotor helps restore consistent throttle response when wear or deposits affect the original part. The component's form factor matches small-model glow engine carburettors that use removable rotors of this size designation.

Installation notes: this part replaces the existing rotor within the carburettor bore, and reassembly should ensure the rotor spins freely without binding and that any retaining clips or screws are secured to factory torque levels. After installation, verify idle behavior and adjust the low/high needles as needed to re-establish correct mixture and smooth idle.

Tuning role: the rotor's surface and fit influence throttle transition and idle stability. A correctly fitted rotor contributes to repeatable needle adjustments and predictable throttle response during on-track running or bench testing.