YS Engine YSF9151 Disc Valve E-Ring for F91AC  [YSF9151]

This small replacement part acts as the retention ring for the disc valve pin on YS F91AC series glow engines, sold here as an RC maintenance item. It is designed to sit in the pin groove and stop axial movement that can upset valve operation.

Fit this e-ring when the original retention element is worn or distorted. During service, make sure the e-ring is fully seated in the groove and that the disc valve pin rotates freely without binding. If the ring is deformed or has lost spring tension, replace it to restore secure retention of the disc valve assembly.

Service note: the e-ring does not change engine timing but is a basic service piece that helps preserve consistent valve movement and predictable throttle response in glow engines.