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

Replacement rotor screw for O.S. small engines

This rotor set screw is a direct replacement part referenced by O.S. Engine OS25081306 and designed for use on the O.S. 35R/C, 40SP, 40P and 50 small-scale model engines listed in the product name. It functions as the mechanical fastener that secures the rotor assembly to the crankshaft or drive hub in compatible RC model engines.

Intended purpose and role: the component provides axial retention for the rotor, helping to maintain timing and balance during normal operation. It is a consumable wear item that should be inspected whenever the engine is disassembled for maintenance or tuning.

Installation and service guidance: confirm compatibility with the model codes shown above before fitting, clean mating threads and seating surfaces, install the screw until the rotor is held securely without play, and inspect for thread damage or head deformation on reassembly. Replace the screw if the head or threads show wear to avoid loosening under running conditions.