Sprocket Tooth Count vs Tire Size Change

[Qdude79]

Gonna go from 22's to 20's on my '85 200X. No major engine mods, other than a fresh rebuild (currently torn down). I want to get new sprockets while I have it apart, should I consider a change in tooth count on either/both ends to compensate for the change in tire size? I understand the 200X's to be low geared anyhow, and smaller tires will add to that. Suggestions? I have no idea how much affect the tire size or sprocket tooth count will have, so numbers would help.

Thanks-

[RIDE-RED 250r]

Im not sure how to exactly calculate how many teeth to change to get the exact gearing with the 20s that you had with the 22s. But if there is clearance, (usually is) you could probably go 2 teeth larger on the drive sprocket. That would get you pretty close to the same gearing with 20s as the stock sprockets with 22s. Just remember, changing the drive sprocket size has a greater effect than changing the driven (rear) sprocket size. If you wanted to gear it a little higher yet, you could drop a tooth or 2 on the rear...

[bkm]

Before you go changing sprockets ride it with the smaller tires. You might like the pick up in acceleration the smaller tires give you.

[Qdude79]

Problem is, I haven't ridden a 200X since I was a kid (and a bit lighter). This one was barely running when I got it and it's now torn apart. I just wanna put new sprockets and leave it. I'm thinking I'll stick with stock, as I prefer grunt over top end.

[RIDE-RED 250r]

Well, if you leave the sprockets at stock numbers of teeth and put 20" tires on the rear, you will definatley get some grunt.

[RubberSalt]

If you want to maintain a similar acceleration/top end, just lower your gear ratio by 10 percent.

example. Your on a 13tooth front and a 40 rear. This gives you a 3.07:1 ratio(40/13=?), if you lower that by 10percent, you get a 2.76 ratio. Now lets see what gets us close to that, sprocket wise.. 39/14=2.78, thats pretty close.

So a 14tooth front and a 39 rear would be close. or a 38 in the rear would give a 2.71- but i like grunt with my 4 strokes.