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

A small replacement retention ring for the disc valve pin on YS F91AC glow engines, supplied as an RC maintenance part. The e-ring locates in the pin groove to prevent axial shift that can affect valve action.

Use this e-ring when the original retention part shows fatigue or distortion. During reassembly, ensure the e-ring is correctly seated and that the pin rotates freely; replace any e-ring that no longer holds spring tension.

Practical note: the e-ring does not influence valve timing settings, but maintaining proper retention hardware helps keep valve movement consistent and supports dependable throttle response.