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AHP 4 Speed Transmission (1 Down 3 Up) - Z50  XR50  CRF50  XR70  CRF70  CT70 SL70

AHP 4 Speed Transmission (1 Down, 3 Up)
Fits Z50, XR , CRF50, XR, CRF70, All years
Pricing: $164.95


AHP 4 Speed Transmission Kit

This radical, 4 speed transmission shift pattern is 1 down, 3 up with hardened gears and shift forks.
The kit is made for those of you wanting to upgrade your stock Honda motors from a 3 speed, to a 4 speed.
It will work with both stock style, semi-auto AND manual clutch kits.
(fits into your OEM Honda cases or your import motor with crank mounted clutch)

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
-Shift drum and hardened shift forks

Arrives assembled for you!

Primary reduction ratio: 3.722

Gear Ratio:
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:

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. Please call with any questions.


  • AHP-ENG38
  • AHP-ENG38
  • AHP
  • New


Shipping Information

  • Item Requires Shipping
  • 6.0 lbs.
  • W8.0000” x H4.0000” x L4.0000”

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