O.S. Engine OS27481900 Needle Valve Assembly for FS-61 FS-70S FS-80 FS-120SE  [OS27481900]

Carburettor needle assembly for O.S. Engine models

This needle valve assembly is an RC-scale carburettor part intended for use with the listed O.S. engine models. It provides a mechanical interface for adjusting low-speed fuel metering and supports mixture setup during bench tuning and engine run-in.

Compatibility is limited to the engine model codes stated in the product name: FS-61, FS-70S, FS-80, FS-120SE. Do not assume fitment to other engines without confirming with the engine's parts diagram or manufacturer documentation.

Installation notes - general guidance:

• Work on a clean bench and remove fuel before servicing the carburettor to reduce contamination risk.
• Replace the needle assembly following the engine's stock carburettor orientation, and secure any retaining clips or seats as originally fitted.
• After installation, use conservative needle changes and verify idle and throttle response in a safe test environment.

Tuning and maintenance tips:

• Make small, incremental turns when adjusting the low-speed needle to locate a stable idle and smooth throttle transition.
• Inspect the needle tip and seat for wear or deposits regularly, and clean with a carburettor-safe solvent if required.
• Record baseline needle settings before making changes so you can return to known values during tuning.