Internal Bearing O-Ring for Rotax Max Kart Engines. This o-ring keeps the needle bearing or nylon bushing from touching the retention nut on the crankshaft during operation of the engine.
Made from humble rubber, this o-ring is very, very important to keep in the engine! Without it, the whole drum assembly can move laterally back and forth and compromise the ability of the bushing or needle bearing to keep the drive sprocket and clutch rotating freely.
This is one part we recommend every Rotax racer have a spare of!
Dimensions of the o-ring are 12mm ID x 2.5mm thickness.