Throttle Stop Screw for O.S. Engine 20D 20F 2FB - OS22681320  [OS22681320]

What this throttle stop does

This compact throttle stop screw is intended for use with carburettors marked 20D, 20F and 2FB on O.S. Engine models. Its role is to provide an adjustable contact point that determines the closed throttle position, helping to keep idle consistent and needle adjustments predictable.

Installation mirrors the original carburettor arrangement where the screw bears on the throttle stop tab or cam. Fitting usually requires removing the existing stop, positioning the new screw, and then adjusting idle with small turns while monitoring engine response.

For best results, change the screw position in fine increments and check that the throttle returns fully and that idle is stable after each change. Clean any fuel residue around the carburettor and inspect thread condition to ensure repeatable settings.