91SR Cylinder Liner for Tuning YSS9105 upgrade for 91SR by YS Engine  [YSS9105]

Tuning and service sleeve for 91SR

The YS Engine YSS9105 cylinder liner is supplied as a replacement sleeve for the 91SR family, intended to restore bore integrity and improve piston seating characteristics. This description concentrates on how a fresh liner affects tuning, throttle response, and routine servicing workflow.

Compatibility: verify the engine is a 91SR before ordering. Fitting the liner will typically mean splitting the crankcase, removing the worn sleeve, and pressing or seating the new part before checking piston-to-wall clearances and ring function. Employ correct RC engine tools and maintain careful technique to preserve component finishes.

Tuning effects: a renewed cylinder surface helps stabilise compression and can make needle adjustments more predictable after installation. When combined with proper break-in and tuning checks, riders often notice tighter throttle response and steadier running under load.

Fit this liner to restore bore condition on YS 91SR engines and validate tuning settings after reassembly for best engine behaviour.