YS Engine YSS9117 Sealing O-Ring - Back Plate for 91SR Series  [YSS9117]

The YS Engine YSS9117 O-ring serves as a purpose-made replacement seal for 91SR-series back plate assemblies on RC engines. It limits fuel and oil escape at the back plate junction, keeping the engine clean and functioning during routine maintenance.

Fit and compatibility: made to match the back plate interface of 91SR engines, this O-ring offers a direct replacement option without altering the back plate's shape. Always check the mating groove and housing for wear before installation.

Installation notes: gently remove the old ring to avoid damaging the bore, clean the contact surfaces, and position the O-ring evenly. A small amount of suitable lubricant will assist installation and reduce the chance of twisting. Complete a static leak test after reassembly.

Maintenance guidance: not a tuning component, the O-ring nonetheless contributes to steady engine performance by preserving proper sealing. Replace the part whenever flattening, cuts, or seepage are observed.