Changing the final drive ratio Harley Evo Sportster Discuss Changing the final drive ratio in the Harley Sportster & Buell forums; I was just wondering after taking a long trip this summer if it would be possible to change my final drive ratio to give me better top end speed with ...

[mikexl883r]

I was just wondering after taking a long trip this summer if it would be possible to change my final drive ratio to give me better top end speed with lower engine RPM. I don't really need to launch off the line and drag race so I was wondering how difficult and where to get parts if I wanted to change the belt pullies. Should I change the front or back pully? How many teeth? Would I need a new belt? I have a 06 883R with python3 exhaust and rejeted with the K&N air cleaner assy. Willing to listen to any advice.

[frisco-rigid]

Hi Bud

One of my books says you run a 28T tranny pulley and 68T wheel pulley..
That gives you a 2.43 secondary ratio..

If you install a 30T tranny pulley that ratio will be 2.266,,, a very big reduction and should reduce RPM's about 240 at 60mph..
A 29T tranny pulley will give you a 2.34 secondary ratio.. You do the math..
I don't know what your primary ratio is so I cannot tell you what your Over-all ratio will be..

Another book says you run a 136T belt, it also says a 1 tooth increase in the tranny pulley will move the rear wheel 1/8" forward.. A 2 tooth increase will move your wheel approx. 1/4" forward..

If you can move the rear wheel 1/4" forward I bet you will be able to use the 30T tranny pulley without getting a longer belt..

If you choose to change to a 65T rear pulley you will need approx. 1/2" to move the wheel to the rear using the same 136T belt.. Doing that will give you a 2.32 rear ratio..
Whatever is easier is usually ah, you know, easier..
Have a ball..