O.S. Engine OS44851000 Exhaust Valve FSa-81 for FS Engines  [OS44851000]

Replacement Valve for FS-Series Engines

The O.S. Engine OS44851000 Exhaust Valve FSa-81 is an RC replacement exhaust valve for FS-series engines, made to reinstate correct valve seating and exhaust operation in nitro model engines.

Intended as a maintenance and minor tuning part, the valve is suitable for hobbyists doing standard upkeep. Make sure the engine has cooled and that mating surfaces are cleaned prior to fitting to prevent foreign material from compromising the seal.

Fitting notes: assess the valve stem and guide prior to installation, use light lubrication on contact areas where appropriate, and follow the engine manufacturer's torque and fitting recommendations for valve train components. Perform bench checks of idle and throttle response after installation to confirm correct timing and sealing.

Tuning role: correct valve seating supports consistent exhaust flow and combustion stability, assisting with jetting adjustments and consistent high-rpm operation. Regular inspection during rebuilds helps sustain predictable engine performance.