Altering Sprocket Sizes

From MCNNinjas

Note: This document was not submitted under the Creative Commons licence

Original (http://www.mcnninjas.co.uk/downloads/Altering%20Sprocket%20Sizes.pdf) by NinjaWasp

The standard sprocket sizes on a J1/J2 are 15 teeth front and 40 teeth rear, giving a final ratio of:

15: 40 = 1 : 2.67

If you want better acceleration, a lower top speed (and better wheelie potential!!) you can make the front sprocket smaller, the rear larger, or a combination of both.

You could fit a 42 on the rear or a 14 on the front these are the most popular and give nearly the same final ratio.

15 : 42 = 1 : 2.80

14 : 40 = 1 : 2.85

Or you could be really radical and go for a 14 on the front and a 42 on the rear giving a final ratio of:

14 : 42 = 1 : 3.00

Bear in mind that if you fit a larger sprocket to the rear, the wheel will have to be moved forwards to accommodate the extra teeth (good for future adjustment).

If you fit a smaller sprocket to the front, the wheel will have to be moved rearwards to accommodate the loss of a tooth (less room for future adjustment).

Finally, remember that if you change your sprocket sizes as above, your speedo will over read by:

9.5% for 15:42

13% for 14:40

22% for 14:42