AHP 4 Speed Transmission Kit 

AHP 4 speed 1 down 3 up transmission, hardened gears and shift forks. This transmission 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 some imported Chinese motors.

Recommended for engine builds starting at 50cc on up to 117cc. 

Fits in: The Z50, XR and CRF50, XR and CRF70, CT and SL70 and ATC and TRX70

Kit comes complete (ready to pop in) with: 
-Main shaft and gears
-Counter shaft and gears
-15 tooth front large spline Z50 style sprocket (re-gear with any Z50 aftermarket sprocket)
-Shift drum and hardened shift forks 

Arrives assembled for you! 

Primary reduction ratio: 3.722 

Gear Ratio: 
          AHP  -  OEM Honda
1 - 3.182 1 - 3.272
2 - 1.706 2 - 1.706
3 - 1.238 3 - 1.238
4 - 0.917 4 - You wish! :)

Quick note: 50 Primary gear count 17/69 or 70 18/67

For reference, check out the Youtube Video of case splitting to install transmission: http://www.youtube.com/watch?v=63skpwY-yTY

Please note: We have put this in many 50's and 70's we have seen in some 70's that you need a 50 kickstart gear (the gear that engages the transmission to start the bike) The 70 gear is a different tooth count than some of the older SL, ST , CT or CL 70's.