AHP 4 speed 1 down 3 up transmission, hardened gears and shift forks. This tranmission kit is made for those wanting to upgrade their stock Honda motors from a 3 speed to a 4 speed. AHP's transmission kit will work with both semi-auto and manual clutches and will fit into a OEM Honda bottom end. Will also fit import motors. Good for 50cc through 108cc. Set comes complete with main shaft, counter shaft, shift drum and shift forks. Primary reduction ratio: 3.722 Gear Ratio: 1 - 3.182 2 - 1.706 3 - 1.238 4 - 0.917