Carburettor Needle Seat for YS 91ST and 91SR - YSS9122 (YS Engine)  [YSS9122]

Overview of the Needle Seat

The YS Engine YSS9122 high speed needle seat is an RC replacement needle valve seat intended for use with YS 91ST and 91SR engine variants. It acts as the wear surface that positions the high-speed needle and helps preserve consistent fuel metering in glow engine carburettors.

This replacement installs into the carburettor body at the needle valve location and should be inspected whenever needle movement, fuel leakage, or erratic high-speed mixtures occur. The part is supplied for hobby-grade RC engines and is not for full-size engines.

During tuning, a correctly seated needle seat supports repeatable needle closures and smoother high-rpm response, assisting with fine carburettor adjustments during break-in, routine checks, or on-site tuning. Replace the seat when sealing fails or wear is visible.