Single Piston Ring OS25303400 Compatible with 50SX-H, 46FX-H, 46SF - O.S. Engine  [OS25303400]

Spare piston ring for rebuilds and routine service

This piston ring is supplied as a direct replacement intended for the O.S. engine variants named in the product title. Use it during maintenance or when rebuilding an engine where the ring shows wear.

To replace the ring, remove the cylinder head and sleeve so the piston is accessible. Carefully remove the worn ring and fit the new one, taking care not to damage the piston, ring groove, or cylinder wall. Work in a clean area and use suitable tools to reduce the risk of nicks or scratches.

Fitting a new ring restores sealing and compression consistency rather than changing running geometry, which helps maintain steady combustion behavior and repeatable tuning. After fitting, check the end-gap and perform a measured run-in before completing tuning changes.

Compatibility is restricted to the model codes listed in the product name; ensure your engine is a 50SX-H, 46FX-H, or 46SF before ordering.