Selecting the proper final drive ratio for the XR650R is important for optimum performance and comfort on your selected terrain. The stock gearing is a 14 tooth on the front sprocket and a 48 tooth on the rear sprocket.
Many owners dual sporting their bike will run a 15 tooth front sprocket and will drop a tooth or two on the front. Riders doing mostly tight technical trail work will drop to a 13 tooth front sprocket and possibly go up a tooth or two on the rear.

The stock ratio of 14/48 is pretty versatile.

A one tooth adjustment on the front sprocket is equivalent to approximately 3 teeth on the rear. So 14/48 gearing is roughly the same as 15/51.

If you would like to calculate the optimum gearing for your bike based on your average and max speeds you can use this Honda XR650R Gearing Calculator. It is an Excel spreadsheet (*.xls) file and will require Microsoft Excel to open. If you do not have Excel then use Open Office – it is a free download (and better in my opinion).

I have preset all the inputs for transmission gearing, chain size, RPMS, and swingarm lengths. Just change out the 14/48 combo for other values and watch the speed calculations change.

Note: Changing to a 15 tooth countershaft sprocket on the XR650R will require your XR650R to have a Case Saver that fits.