Yamaha Xmax 300 O-Ring (B74-E2439-00)

The Yamaha XMAX 300 O‑Ring (B74‑E2439‑00) is a precision sealing ring used in specific fluid or air joint applications within the engine or transmission of the XMAX 300. This small but crucial component forms a tight, leak‑proof seal between two mating surfaces — such as oil passages, coolant joints, or breather connections — helping prevent fluid leaks, contamination, and loss of pressure.

Made to Yamaha’s exact specifications, this O‑ring is manufactured from durable elastomer material that resists heat, vibration, fuel and oil exposure, and repeated compression. Over time, O‑rings can harden, crack, or lose their elasticity due to thermal cycling and normal wear, which can lead to seepage and reduced performance of the affected system. Replacing a worn or compromised O‑ring with this genuine‑style Yamaha part restores proper sealing, supports efficient operation of the scooter’s systems, and helps maintain overall engine reliability and cleanliness.