Last night i noticed i have a 39T rear...i'm not sure what the front is

 

13/38 is stock gearing.

I change back and forth between 12/13/14 tooth front sprockets depending upon the riding and racing I am doing, and what size tires I have on the back.

Chris 00' TC Racing 300EX

 

How much topend did i lose?

20" rears, 13/39 gearing

 

20" Holeshot tires are roughly about the same size as 22" Otusu(stock) tires. The only difference is that the Holeshots are not as rounded as the stockers.

13/38 - 2.92 final drive ratio
13/39 - 3.00 final drive ratio

Top end will not change enough too notice.

If you install 18" tires, or 22" tires. Then you will notice a change in top end.
Changing 3 teeth in the rear sprocket is equal to changing 1 tooth on the front sprocket.

Chris 00' TC Racing 300EX

 

Thanks for the info.

I am going to stay with 20" bandits for my next tires. And when i replace my sprockets this winter i'm going back to 14/38 so i can pick up more topend

Thanks again