120AX Multi-Piece Gasket Kit OS29121400 O.S. Engine  [OS29121400]

120AX seal pack explained

This gasket pack is designed for the 120AX series and is listed under the O.S. Engine part number OS29121400. Use it when you strip, inspect, or rebuild a compatible 120AX motor.

Compatibility is limited to engines bearing the 120AX designation; always confirm the exact model code before fitting parts. The set reinstates sealing between components such as the crankcase, head, and backplate following maintenance or part replacement.

Installation guidance: remove any old gasket remnants, check all mating surfaces for bending, cracks or other faults prior to fitting the new gaskets, and adhere to O.S. Engine torque and assembly recommendations when reassembling. Correct sealing helps keep compression stable and supports consistent tuning response.

Performance note: while gaskets do not alter tuning settings themselves, renewing seals is fundamental to maintaining stable compression and predictable needle-valve behavior during tuning and running.