YS Engine YSF9156 Low-Speed Needle Valve for .91 .120SC .140 Glow Engines  [YSF9156]

Precision low-speed needle for model glow engines

This RC-scale low-speed needle valve is a direct replacement for carburetors that accept the YSF9156 needle profile. It governs the low-throttle fuel metering circuit used at idle and under light-throttle running on .91, .120SC and .140 glow engines.

Fit this part when you need a service replacement or when fine low-speed mixture control is required during tuning. The valve only affects the carburetor low-speed circuit; small needle movements change idle mixture and transitional running, which helps stabilize idle, reduce bogging at low throttle and improve throttle response in the lower power band.

Installation takes place at the carburetor low-speed needle seat and should follow the engine or carburetor manufacturer's instructions, with tuning done incrementally while observing engine response. This item is an RC-scale accessory intended for model glow engine use only and is not suitable for full-scale engines.