HI, I bought a pair for my 2000 mxz 600 but heard that in some sleds you have to trim the rails back. Will I have to do this and if so how much?
thanks.

Yes, for both the 9 and 10 tooth drivers you'll have to trim back the rails. If your only replacing the sprocket with an extroverted one, use this simple rule of thumb:

- Measure the length of just one of the extrovert flanges / sprokets and subtract that from the rails to obtain the clearance you need.

But, if its a new diameter (like a 10 tooth);

- Measure the length of one of the extrovert flanges / sprokets plus the differance in the new radious and subtract that from the rails to obtain the clearance you need...

As long as you have between 1" to 1.5" of clearance with the sled level with no load on the suspension, you should be OK.

I got the original 9 tooth, but by sprocket/flange length do you mean the tooth that drives through the window or the things that drive by push the rubber knobs?if its the ones that drive the knobs do I cut off the length of one of those teeth or the length of the two teeth?
sorry about all the questions
thanks.

Hope this picture works.
if not the website I got them from is
www.hiperf.com/ acatalog/Online_Catalog_Drive_Sprockets_102.html
there called the no slip drive sprockets.

Sorry I wasn't clear enough. Flange = projection, protubrance, outcrop, etc.. So the "teeth". Don't worry about the introverted "teeth", it's the extroverted "teeth" you are concerned about. Clear?