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elementary gearing class 101

782 Views 3 Replies 4 Participants Last post by  jbranson
so when iwas at Loudon I had changed gearing because of the enormous torque that the new engine puts out. Running 17/40, used to be 16/42. But I found that I was hitting 5th at near the end of the straight. So does this mean I should go to 17/42? Bigger in the rear?

I always get confused here. What's an easy way to think about this?

I noticed tht Matt camelhairy went from a small rear to a big rear sprocket to get up t. 3 hill faster, but that of course put him screaming on the straight.

As for the MT, I was in 6th (maybe it was 5th but I think it has a 6 speed) before getting to start finish. Should I put on a smaller rear sprocket? Or if I do that will I not be able to get up the hills?
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This site has a great chart for the Yammie 500. It shows the XT/TT, and I'm not sure, but I think the internal ratios for the SR tranny may be different. You could probably find that out from one of the thumper sites, or ask Mark at
But the top section of the chart will give you a good comparison of final drive ratios. I think Sprocket Specialists has a similar chart.

How much low speed acceleration do you anticipate? I like to keep a lower number on the front for better accel off the turns. Of course I only have to setup for one gear, but still, I would think you could go down to a 16, maybe even a 15 front, then find the right rear sprocket to get you into fifth halfway down the straight. Particularly if you can get onto the straight in 2nd...
Your engine has enough torque that once you leave the line you don't need 1st gear anymore.


Edited by - FR on May 03 2007 3:10:40 PM
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