OS25081306 Rotor Set Screw for O.S. Engine 35R/C, 40SP, 40P, 50  [OS25081306]

Overview of the rotor set screw

This rotor set screw is a direct replacement part identified as O.S. Engine OS25081306 and is suitable for use with O.S. 35R/C, 40SP, 40P and 50 small model engines listed above. It secures the rotor assembly to the crankshaft or drive hub on compatible RC engines.

Intended purpose and role: the set screw provides axial retention for the rotor to help maintain correct timing and running balance. It is classed as a serviceable wear item and should be checked at every engine strip.

Installation and service guidance: confirm the engine codes are compatible before fitting, clean the mating threads and seating faces, tighten the screw until the rotor is held without play, and check for thread or head damage on reassembly. If any wear is found, replace the screw to prevent loosening while the engine is running.