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

Rocker arm shaft screw for YS 120/140 engines

This YS Engine YSF1216 part is an RC-scale rocker arm shaft screw intended for use with 120 and 140 class RC engines as indicated by the product name. It is a replacement fastener designed to secure the rocker arm shaft and support consistent valve linkage alignment during routine maintenance or engine rebuilds on model engines.

In practical service, the screw serves a focused role: it locks the rocker arm shaft in position so the rocker arms can transfer motion from the cam/valve system to the valve train. When servicing a 120 or 140 class RC engine, inspect the screw for thread damage, head wear, or corrosion before reuse and replace if any defects are found to maintain precise valve timing and motion.

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-scale replacement component for model engine maintenance and tuning tasks rather than a performance upgrade on its own.