YS F91AC Back Plate Screw Replacement - YSF9153 (YS Engine)  [YSF9153]

Replacement back plate screw for F91AC

This YS Engine YSF9153 back plate screw is an RC-grade replacement part intended for the YS F91AC engine rear cover. It serves as the dedicated fastener to secure the engine back plate and adjoining components, and is supplied as a hobby spare item.

Fit this screw when the original back plate fastener is worn, lost, or damaged. Installation requires correct seating and cautious tightening to protect threads and the mating surfaces of the engine housing.

For servicing and tuning sessions the back plate screw helps keep the rear cover correctly positioned so internal adjustments and port timing remain stable. Check the fastener after runs to ensure it is secure and the thread engagement is intact.