O.S. Engine 61E-R and 91HZ-R Carburettor Mixture Valve OS29088300  [OS29088300]

Carburettor Tuning Valve Details

This mixture control valve assembly replaces the original component on O.S. Engine 61E-R and 91HZ-R carburettors, providing a means to adjust fuel/air balance at low throttle settings. The part helps reduce idle hunting and smooths throttle transitions when properly set.

Fitted as an aftermarket replacement, the valve works with the existing carb mounting and linkages used by the listed O.S. models, so you can correct mixture behaviour without fitting a new carburettor. Typical fitting is part of routine servicing or when needle adjustments no longer deliver stable idle.

Tuning note: adjust in small increments, then run the engine under safe test conditions to judge the effect. Ensure linkages move freely and sealing surfaces are clean to avoid false readings caused by air leaks.

Before installation, confirm the OS29088300 designation matches your engine. Conduct bench tests or short tethered runs to verify the mixture outcome prior to full operation.