O.S. Engine OS4A081600 Mixture Control Valve 70T FG30  [OS4A081600]

Carburettor mixture valve overview

This mixture control valve is an RC-scale carburettor replacement part designed to regulate the fuel/air mixture at the carburettor. It carries the 70T FG30 marking and is supplied as a single service component for maintenance or tuning of compatible O.S. carburettor assemblies.

In use, the valve gives a direct, user-accessible way to alter mixture richness. Installed in the carburettor assembly it influences idle quality and low-speed throttle response, enabling fine mixture adjustments without needing to replace the entire carburettor.

Installation notes: remove the fuel tank and disconnect any linkage as required by your engine service routine, gain access to the carburettor, and swap the mixture valve following the engine maker's safety guidance. Confirm correct seating and alignment of the linkage before any initial running.

Tuning tips: make only small changes and test throttle response on the bench or with the model restrained. Listen to engine tone and monitor idle stability, adjust in small increments, then check for fuel leaks and tighten any retaining fasteners.