F91AC Disc Valve Pin E-Ring YSF9151 by YS Engine  [YSF9151]

This compact stainless e-ring is the retention element for the disc valve pin on YS F91AC series glow motors, supplied as an aftermarket service item. It fits into the pin groove to prevent axial movement that can impair valve operation.

Replace the e-ring if it shows wear or deformation. On installation, verify the ring seats flush in the groove and that the pin turns smoothly without binding; replace any ring that fails to maintain spring tension.

Note on performance: the retention ring itself does not change valve timing, but correct retention maintains steady valve movement and consistent throttle response during operation.