O.S. Engine OS29121400 Gasket Set for 120AX  [OS29121400]

Replacement gasket kit for 120AX engines

This gasket set is a replacement kit for the 120AX engine family and is supplied under the O.S. Engine part number OS29121400. It provides the multi-piece seals used when carrying out engine teardown, inspection, or a full rebuild on matching 120AX units.

Compatibility is restricted to engines designated 120AX; match the exact model code before ordering. The kit restores sealing between mating parts such as the crankcase, cylinder head, and backplate during maintenance or after part replacement.

Installation guidance: clean all mating surfaces of old gasket material, check for warpage or other damage before fitting the new pieces, and follow O.S. Engine torque and assembly specifications for fasteners at reassembly. Proper sealing preserves compression and predictable engine behaviour across tuning adjustments.

Performance role: gaskets do not directly change tuning settings, but correct seals are essential for stable compression and consistent needle-valve response, so renewing worn gaskets is standard practice to maintain engine consistency during setup and service.