81-08 SUZUKI RM250: Sunstar Steel Rear Sprocket (520 / 42T) Sunstar is the largest O.E.M. supplier of sprockets and brake rotors in the world. In fact, your motorcycle probably came from the factory with a Sunstar sprocket. Need a reason to choose Sunstar? Every Sunstar product is imbued with superior quality, uses an exclusive heat-treatment and quenching process, is based on advanced research and design, and is sold at an added value price. Manufactured using only the highest quality 1045 high-carbon steel.