YS Engine YSF1251 Regulator Screw Set for 91/120/140 RC Engines  [YSF1251]

Regulator Screw Set - Quick Overview

This regulator screw set is a purpose-built RC replacement kit specified for 91, 120 and 140 engine sizes, designed as direct-swap hardware when original regulator screws show wear or need renewal. The pack is intended for model-scale engines and their carburetor or regulator mountings.

Check fitment: compatibility is limited to the 91, 120 and 140 size designations shown in the product name, so verify your engine references those numbers before fitting. The text focuses on practical fitment and field use for RC engines without suggesting other applications.

Installation tips: use the correctly sized hex driver, thread screws slowly to avoid cross-threading, tighten to a snug seating and do not over-torque, inspect linkage alignment after fitting and run the engine at low throttle to verify a stable idle and consistent response.

Tuning role: replacing worn regulator screws restores repeatable adjustment points and reduces play in linkage or carburetor linkages, which helps maintain stable needle or regulator settings during setup and trackside servicing.