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

Rocker arm shaft screw for YS 120 and 140 engines

This YS Engine YSF1216 component is an RC-scale rocker arm shaft screw intended for use with 120 and 140 class RC engines as shown in the product name. It serves as a replacement fastener that holds the rocker arm shaft in place and supports consistent valve linkage alignment during routine maintenance or engine rebuilds on model engines.

In service the screw's role is focused: it locks the rocker arm shaft so the rocker arms can transfer motion from the cam or valve system into the rest of the valve train. Before reuse inspect the threads, the screw head, and check for corrosion; replace the screw if any defect could affect secure fastening or alignment.

Installation notes and tuning context: install the screw so the rocker arm shaft is aligned without side load, verify smooth rocker movement after tightening, and re-check clearance during initial run-in. This part is intended as a direct replacement component for model engine maintenance rather than a performance upgrade.