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

Rotor insert for small-model carburettors

The O.S. Engine OS25881200 carburetor rotor is engineered for RC carburettor assemblies that take a 40L rotor marked 55Hz and serves as the rotating element that meters air and fuel at varying throttle openings.

Supplied as a replacement item for maintenance, the rotor helps recover consistent throttle feel when the original component is degraded by wear or contamination. The part conforms to the form factor used in small glow engine carburettors featuring removable 40L rotors with the 55Hz designation.

Fitting instructions: remove the old rotor and install this replacement ensuring free rotation and correct securing of any retaining clips or screws. Once refitted, test idle and fine tune the low and high needles as necessary to restore correct mixture settings and smooth idle operation.

Effect on tuning: rotor clearance and surface finish influence throttle response and idle stability. Proper installation aids in achieving repeatable needle settings and reliable throttle performance during operation and setup.