Spears Racing’s 415 drive chain kits are for the Kawasaki EX250/300/400 Ninja and the Yamaha YZF R3 2015+. This kit will reduce your unsprung weight/rotational mass by over three pounds.
Spears Racing 415 Drive chain kits is used by several BSB Junior Supersport,Motoamerica, WSS300 and CSBK Lightweight Sportbike Championship teams as well as hundreds of club level race teams around the world.
Since the inception of this amazing product Spears Racing riders have been able to set several track records along with winning several class championships and National #1 plates.
This kit comes standard with an 18t front sprocket (17 and 19 optional) and is available with 45,46,47,48,49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 and 60 tooth rear sprockets.
When making your choice for the Yamaha R-3 you can go with the 18t/55t (3.05) this will be the closest to the OEM gear ratio of 3.07 (14/43).
When making your choice for the Kawasaki EX300 you can go with the 18t/54t (3.00) this will be the closest to the OEM gear ratio of 3.00 (14/42).
When making your choice for the Kawasaki EX400 you can go with the 18t/53t (2.94) this will be the closest to the OEM gear ratio of 2.92 (14/41).
*** Just remember that if your looking for more of a drive off the corner you will add a tooth or two.***
The rear sprocket is made from the highest grade aerospace quality 7075-T651 aluminum and weighs (9.64 oz./274g depending on tooth count). It is machined not stamped, this way you don’t have to worry about it being ” True to the alignment” of your chain and front sprocket (no wobble).
The drive chain is a EK415R racing chain and has a tensile strength of 4,610, and weighs 2.16 lbs./982 Gms. for the Yamaha R-3 and 2.01lbs./913 Gms. for both the Kawasaki EX250/300/400cc.
The steel counter shaft sprocket is drilled to be the lightest steel sprocket on the market (sprocket weights 4.6oz./130 Gms. 18 Tooth)
The large reduction in weight and friction translates to .6/.7 extra HP being transferred to the ground instead of being lost to friction. You also will notice faster acceleration and better handling by reducing the gyroscopic effect of the rotating mass.