Javascript Gearing Calculator
Primary Gear Front Sprocket   
Rear Sprocket Rear Wheel Dia

1 Gear MPH
2 Gear MPH
3 Gear MPH
4 Gear MPH
5 Gear MPH
6 Gear MPH


Default values are for a 1996/7/8 or 1999 XR400R.

The XR400R RPM range is up to 9,200 RPM before the rev limiter cuts in - need to double check that?

Realistic dyno runs show 8 to 8,300 as being the max working RPM, unless engine work is carried out to obtain more revs.

Wheel diameter can vary subject to tyre choice. Measure roll circ and use C=Pi times D to calculate, where Pi is 22/7

HRC kit Primary Gears are 24/64 or 2.666 to 1 ratio.

To return the script default values use refresh in your browser plus the control key.

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