Vortex CK6316 Racing Sprocket Kit HFRS - Hyper Fast Steel 520 Kit, 1 Down in the Front, 2 Up Steel Rear Fits Yamaha YZF-R6 06-15 Kit Gearing, Ratio 3.13, Front 15 Rear 47 OE Gearing, Ratio 2.81, Front 16 Rear 45 Kit Components, Front 3271-15, Rear 435S-47, Chain 520SV3-114