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

Replacement mixture valve details

The mixture control valve is a service part for RC carburettors, marked 70T FG30 and supplied as a single unit. It is intended for maintenance and tuning of O.S. FG30-type carburettor assemblies where fine mixture adjustment is required.

When used, the valve provides a user-accessible method to change fuel mixture richness, which affects idle quality and low-speed throttle behaviour. This lets you make precise mixture corrections without swapping the whole carburettor.

Installation notes: follow the engine manufacturer's service guidance—remove or secure the fuel tank, disconnect linkages as necessary, access the carburettor and replace the mixture valve. After installation verify seating and linkage alignment prior to any running.

Tuning tips: proceed with minor adjustments and evaluate results under restrained conditions. Listen for changes in engine note and check idle stability, refine slowly, then inspect for fuel leaks and ensure retaining parts are tightened.