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

O.S. Engine needle valve part

This needle valve assembly is a carburettor component intended for the stated O.S. engine models. It is used to adjust low-speed fuel metering and to help achieve the correct mixture during bench tuning and break-in.

Compatibility is confined to the engine model codes shown in the product title: FS-61, FS-70S, FS-80, FS-120SE. Do not assume it will fit other engines without checking the manufacturer's parts breakdown.

Installation notes - general guidance:

• Perform work on a clean bench and evacuate fuel from the carburettor before service to avoid contamination.
• Install the needle following the carburettor's original orientation and secure any clips or seats exactly as fitted originally.
• After installation, approach needle adjustments conservatively and verify idle and throttle response in a controlled area.

Tuning and maintenance tips:

• Turn the low-speed needle in small increments until you achieve a steady idle and smooth transition through the throttle range.
• Periodically inspect the needle tip and seat for wear, corrosion or residue; clean with a suitable carburettor cleaner where appropriate.
• Keep written records of your baseline needle positions so you can revert to known settings during troubleshooting.