Would a 15 tooth countershaft sprocket get it back to or near stock gearing? If not what combination of sprockets f/r would?

 

A 15 would give you taller gearing than stock with 20" tires. That's what I run on my Warrior. I first tried a 14 when switching to 20" Bandits and the gearing was pretty close to stock but I wanted a little taller ratio for top end.

 

When you went to the 15t did you have to cut part of the case? I was told that a 15t doesnt fit and you would need to cut part of the case to make it work. If you want a stock gearing, I think you are going about it the wrong way..
Gearing at 13:40 with a 21 in tire would be about the same as a 12:39 with a 20. I am not absolutly posative, but will look into this more.

 

It is not necessary to modify the case, at least on the 97. Not sure what you mean by "going about it the wrong way". For taller gearing one uses a bigger c/s sprocket or a smaller rear, or a combination of the two. I believe your hypothesis is incorrect or the math is. In any case, if you check Sidewinder Sprocket's web page, their chart will give you any combo you wish.
Yamaha does list a 16 tooth c/s sprocket but I would have some doubt as to its fit.
Bottom line, if taller gearing is what you want a 15 tooth c/s with a true 20" tire will give it, no question. Conversely, the 13 tooth on my Raptor is producing quite tall gearing, especially in first gear and I'm debating the use of a 12 tooth to make it more tractible in tech. sections.

 

Warrior1369 wanted stock gearing, not taller..Your probably right no the me being wrong on the math though

 

I understand that. If you read my original reply, I mentioned that the 14 tooth with a true 20" tire seemed to be very close to stock 13 w/22" tires. I now run a 15 on 20" Bandits & the gearing is taller in my seat-of-the-pants experience.

 

I'm probably going to get both but I'll prob. end up using the 14,thanx for your help!

p.s. w/ a little more low end I'll totally smoke my brothers Lakota!