91SR Cylinder Sleeve Upgrade YSS9105 compatible with 91SR by YS Engine  [YSS9105]

Durability sleeve for 91SR engines

The YS Engine YSS9105 liner serves as an aftermarket replacement sleeve for the 91SR engine family, intended to refresh the cylinder bore and support consistent ring seating. The following guidance highlights material considerations, fitment notes, and how a new sleeve contributes to dependable engine operation.

Compatibility: ensure the engine code reads 91SR before purchase. Installation generally requires careful disassembly, removal of the worn sleeve, and pressing or seating the replacement into the crankcase, followed by checks on piston clearance and ring seating. Use appropriate RC workshop tools and observe safe assembly practices.

Durability benefits: a correctly fitted liner restores bore roundness and surface finish, which helps maintain compression and reduces uneven wear. When combined with correct tuning and fresh rings, it can extend service intervals and improve day-to-day consistency.

Use this liner to recover bore condition on YS 91SR motors and inspect mating parts during reassembly to maximise service life.