O.S. Engine OS4A081600 mixture control valve 70T FG30  [OS4A081600]

Mixture control valve for RC carburettors

This mixture control valve is an RC-scale carburettor replacement part intended to manage the fuel/air mixture at the carburettor level. It is identified by the 70T FG30 marking and is supplied as a single component for maintenance or tuning tasks on compatible O.S. carburettor assemblies.

Functionally, the valve provides a user-accessible point to adjust mixture richness during tuning. When installed in the carburettor assembly it affects idle and low-speed response, allowing incremental mixture changes without replacing the entire carburettor unit.

Installation notes: remove the fuel tank and disconnect linkage as required by your engine’s service procedure, access the carburettor, and exchange the mixture valve following the engine maker’s safety steps. Verify valve seating and linkage alignment before testing at low throttle.

Tuning tips: make small adjustments and test throttle response on the bench or with the model restrained. Observe engine note and idle stability, then refine mixture in small increments. After tuning, confirm there are no fuel leaks and secure any retaining hardware.