crf50 4 speed transmission upgrade????

my bike is an urban cruiser wheelie bike. I dont have enough top speed and dont want to change the sprocket size due to the loss of torque.

I would like to keep my gearing the same but simply add a fourth gear....

Enter the ebay search....

I found a 1 down 3up gear set for the 50's made by ahp. $150.00

it has the following ratios:

Primary reduction ratio: 3.722 Gear Ratio: 1 - 3.182 2 - 1.706 3 - 1.238 4 - 0.917

(stock 1st gear: 3.272)

(stock 2nd gear: 1.666)

(stock 3rd gear: 1.190)

does anyone have any experience/insight with this or any aftermarket transmission gearing?


Well, if you want to add a 4th gear and keep the first 3 ratios, then essentially you will be losing torque in 4th gear. So you could get the same result for the price of a sprocket. Or you could buy the AHP 4 speed, or a 4 speed from another Honda bike. As far as I know, there is no 4 speed with the same first 3 ratios as the Honda 3 speed.

we have the same kit ,good set up for mildly built 50 motors

thanks for the info qwoke-q...

my main purpose in the transmission upgrade it to go faster than my friend top speed, but I dont want to loose them off the line.

to keep close to my current gearing could I go with the above upgrade and then drop a few teeth on the rear sprocket?

If you keep your current gearing, you will not gain or lose any speed or torque. But you will have to shift one more time and essentially you will have paid $150 and not gained performance.

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