I find this site useful for calculating the different sprocket sizes.

 

Thanks Zart. I took a look at the site. I switched to the 17T CS sprocket awhile back. Lost a little snap on the bottom end but overall I am happy with the performance.

 

To make a tourer out of my ZRX1200, I dropped 4 teeth on the rear. At 120k/hr, went from 4500 down to 4000rpm. With a 5 speed box, fourth became what 5th use to be.

Thinking of the same sort of mod for the XRT...I'll need to get the bike first.:wink2:

 

That and your speedometer will be more accurate. They get a bit optimistic in the upper register.

 

I don't understand why you say that the speedometer would be more accurate.??
Speedo cables are usually driven of the front wheel. Modern electronics are usually taken from the ABS sensor.
Changing sprocket size would not affect either.

I've heard that some bikes speedos are driven out of the gearbox, got no idea which ones though.