Vortex CK6364 Racing Sprocket Kit HFRS - Hyper Fast Steel 520 Kit, 1 Down in the Front, 2 Up Steel Rear Fits Yamaha YZF-R1 09-14 Kit Gearing, Ratio 3.06, Front 16 Rear 49 OE Gearing, Ratio 2.76, Front 17 Rear 47 Kit Components, Front 3289-16, Rear 435S-49, Chain 520RV3-120