O.S. Engine OS21285900 Needle Valve Assembly carburettor part for OLD-10A,10D  [OS21285900]

Needle valve assembly for OLD-10 series

This needle valve assembly is an RC-scale carburettor replacement designed for the OLD-10A and OLD-10D carburettors. It serves as the metering element that lets you refine fuel delivery during tuning and routine maintenance. The text focuses on fit, function, and how the part integrates into fuel control systems on nitro RC engines.

Fit and compatibility are limited to the named carburettor models, so confirm your carburettor type before ordering. In service, the assembly provides the adjustable needle interface used to set idle and part-throttle mixtures; replacing a worn assembly restores predictable needle response without changing other carburettor components.

Installation is straightforward for those familiar with carburettor disassembly, typically involving removal of the carburettor top, extraction of the old needle assembly, and reinstallation of the new unit with careful seating and light testing of idle and throttle response. Use small adjustments when tuning and verify engine behavior in a safe outdoor area designed for RC nitro use.