YS 91ST/91SR Needle Seat Carburettor Replacement - YSS9122 by YS Engine  [YSS9122]

YS Needle Seat Overview

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

This component fits into the carburettor body at the needle valve bore and should be checked whenever needle play, fuel seepage, or inconsistent high-speed mixtures are noticed. It is supplied as a needle seat replacement for hobby-grade RC engines.

When tuning, a correctly seated needle seat contributes to reliable needle seating and smoother high-rpm response, aiding finer carburettor adjustments during break-in, routine servicing, or track-side setup. Replace the needle seat if the needle no longer seals reliably or if visible wear appears.