YS Engine YSS9122 High Speed Needle Seat 91ST 91SR Needle Seat Part  [YSS9122]

Needle Seat for YS 91ST/91SR

The YS Engine YSS9122 high speed needle seat is an RC-scale replacement needle valve seat intended for use with YS 91ST and 91SR engine models. It functions as the wear surface that locates the high-speed needle and helps maintain repeatable fuel metering in glow engine carburetors.

This part installs into the carburetor body at the needle valve location and should be inspected whenever needle play, fuel leaks, or inconsistent high-speed mixtures are observed. The component is described as a needle seat replacement and is intended for hobby-grade RC engines rather than full-size engines.

For tuning, a properly seated needle seat contributes to predictable needle seating and smoother high-rpm response, assisting with finer carburetor adjustments during break-in, routine maintenance, or track-side tuning. Replace the needle seat when the needle no longer seals consistently or when wear is visible.