O.S. Engine OS22826133 O-ring for Exhaust Adaptor No.4 (21RX,21RG)  [OS22826133]

Exhaust adaptor O-ring for 21RX/21RG

This O-ring is a small-scale RC replacement seal intended specifically for Exhaust Adaptor No.4 used with the 21RX and 21RG units. It functions as a sealing element between the adaptor and the exhaust manifold to prevent leaks that can affect exhaust flow and consistency on model engines.

Compatibility is limited to the adaptor designation shown in the product name, so confirm your adaptor is No.4 and the engine model is 21RX or 21RG before fitting. The part is supplied as a single O-ring and is meant as a routine service item rather than a performance upgrade.

Installation notes: inspect both mating faces for old gasket remnants, dirt, or burrs, seat the O-ring evenly in the adaptor groove, and avoid twisting or pinching the ring when assembling. Replace the O-ring if it shows compression set, cuts, or glazing. A correct seal helps maintain repeatable exhaust conditions during tuning and track use.