RK Vortex O-Ring Alu OE Chain and Sprocket Kit for YAM YFM350X (Warrior) 89-04 RK Chain Model: 520EXW-98 RK Chain Type: Gun Metal O-Ring Vortex Front Sprocket: Steel 13 Tooth Vortex Rear Sprocket: Aluminum 40 Tooth Bike's Stock Gearing: 13-40