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

This tiny stainless retention ring secures the disc valve pin in YS F91AC glow engines and is offered as a replacement service part. It fits into the pin groove to prevent axial movement that can compromise valve operation.

Install this e-ring if the original shows signs of wear or loss of spring action. Confirm the ring seats fully and that the pin moves freely; any deformation or slack indicates the ring should be replaced to maintain secure valve retention.

Operational note: the e-ring does not alter engine timing, but correct retention contributes to consistent valve action and dependable throttle behaviour in RC glow engines.