UMS 7-77cc O-RING INLET PIPE ( X 10 QTY / PACK)

This is the o-ring inlet pipe for the UMS 7-77cc engine, the seven-cylinder 77cc four-stroke radial from UMS.

The part itself is the O-ring sealing the inlet pipe joint.

Why it is replaced: a hardened O-ring at this joint is a classic source of a lean-running cylinder on a radial. Supplied as a pack of 10, which is how these small parts are normally bought — you rarely need just one.

Fitting note: Renew on every disturbance and check the groove for damage.