Rocker Arm Shaft Fixing for 120/140 RC Engines YSF1216 by YS Engine  [YSF1216]

Service screw to secure rocker arm motion

The YS Engine YSF1216 part is a rocker arm shaft screw for use on 120 and 140 class RC engines, intended as a direct replacement during servicing. It is designed to clamp the rocker arm shaft and support correct valve linkage alignment when performing routine maintenance or engine rebuilds.

Functionally the screw locks the rocker arm shaft so the rocker arms can transmit cam or valve movement into the valve train. Prior to reuse check the thread condition, the screw head, and for any corrosion; if any of these areas are compromised replace the screw to maintain precise valve motion.

Tuning and setup notes: fit the screw so the rocker arm shaft sits true without side load, confirm free rocker travel after tightening, and re-check clearances after initial break-in. The item is a maintenance fastener and not intended as a tuning upgrade on its own.