YS Engine YSF9135 Rocker Arm Screw for F91AC  [YSF9135]

This YS Engine YSF9135 rocker arm screw is a direct replacement fastener made for the F91AC engine family. It secures the rocker arm area and is intended for routine maintenance and light tuning on small model engines.

Use on F91AC-pattern engines where the original component is specified. Confirm thread diameter and engagement depth before fitting to prevent interference with valve parts. The component functions as a mechanical fastener to hold the rocker assembly and maintain correct valve motion geometry during setup and adjustment.

Installation note: remove the valve cover and rocker assembly as required, align components and tighten to the engine manufacturer's torque guidance, then verify valve clearance. When tuning, make incremental rocker adjustments and recheck clearances after each change.