Sproket set up

[CGriff]

YA hey there guys.. I have a 2003 400ex and i was wondering what a good tooth counter pre front and back sprocket would be for some higher top end? Ty.
CGriff

[northwest Texas]

To go one tooth smaller on the rear is a 2.4% increase. With a stock engine I don't think any more (or less) will be beneficial. That changes your ratio from 2.53 to 2.47

To go two teeth smaller is a 5.1% increase and I don't think you'd pull that on anything but firm ground i.e. road. That changes from 2.53 to 2.40

One tooth larger on the front is a bigger difference at 5.9% (2.53 to 2.38)

[vett_09]

Going with a 16T on the front sprocket is probably better, but you will need to grind down the case saver. Taller gearing will give you higher top speed potential, but you'll also need a motor that can pull it. I don't know what kind of difference you'll see with out engine mods because I installed my 16T after I went to a 416.

[CGriff]

Ahhhh I see... i was actually looking at a 416 kit on ebay that cam with the gaskets piston, and a stage 1 hot cam... did u find u got a worth while result with going just 1 size over? Ty for your help all.
CGriff

[vett_09]

For me, yes. Because a lot of the riding I do is at higher speeds. A lot of the areas I ride in have long straight trails nearly as wide as a road. There is a noticable top end difference between the 15T and 16T. If you use the search feature you can probably find a gearing converter/calculator. Just input what sprocket sizes you run or want to run with the tire size and it gives an estimated top speed for each gear. There are other variables you can change, but I can't remember off the top of my head.