Race-Driven Front and Rear Steel Sprockets. You will receive 1 - 13 tooth front steel sprocket and 1 - 40 tooth rear steel sprocket, these sprockets have a 520 pitch and will fit the following: 1987 1988 Yamaha YFM350 Warrior. All Race-Driven Drive Sprockets are manufactured to meet or exceed OEM specifications and are produced using hardened S45C steel to give you years and years of trouble free service. Please make sure when purchasing sprockets you do so according to your ATV and riding style. You can also purchase sprockets that will give you more take-off speed or top-end speed. Race-Driven is committed to bringing the highest quality products to all riders at an affordable price. Customer Driven – Quality Driven – Race-Driven.