Vortex CK6317 Racing Sprocket Kit HFRS - Hyper Fast Steel 520 Kit, 1 Down in the Front, 2 Up Steel Rear Fits Yamaha YZF-R6 / S 03-09 Kit Gearing, Ratio 3.33, Front 15 Rear 50 OE Gearing, Ratio 3, Front 16 Rear 48 Kit Components, Front 3271-15, Rear 435S-50, Chain 520SV3-116