need help with gearing

[-TheDude-]

I have a 400ex and just got done with a 416 kit, je piston, wiseco valves, crf 450 timing chain and stage 2 hot cam. I was running 14/39 to get some low end. now it has way to much power for that gearing, its like theres no first or second gear, i was wondering what you guys ran to save me from buying a bunch of sprockets..... o i race xc

[zip69_1999]

Well it depends on what kind of riding you do ! I do alot of trails and I run 16/38 it works pretty well, but the case saver doesn't fit, I also run 15/38

[3400ben]

Originally posted by zip69_1999
Well it depends on what kind of riding you do ! I do alot of trails and I run 16/38 it works pretty well, but the case saver doesn't fit, I also run 15/38


The case saver will fit you need to grind on the inside about a 1/16" off.

[slightlybent47]

I have basically the same build and run a 15-36 with 18'' tires.

Here is a calculator that might help you.
http://home.earthlink.net/~gellett/400ex.htm

[ish416]

I run stock 15/38. Seems to be about the best all around gearing that I have found. That is with 20 inch rear tires.

[JOHNDOE83]

I love that gearing calculator, I use it all the time...lol

You can use it to find what rpms your putting out with your gearing, mine puts out 8800rpms...all you need to know is what your top speed is by gps, car or radar and your gearing and tire size.

Then you change the numbers in the rpms spot till your speed on the calculator matchs your 400ex top speed and walla, you have your max speed rpms.

[-TheDude-]

I don't care much about top speed at all. I race xc the only thing I care about is that my gearing is correct so that when I go up hills and such I don't bog down in second and have to drop to first and go up the hills with no speed.

[slightlybent47]

Originally posted by -TheDude-
I don't care much about top speed at all. I race xc the only thing I care about is that my gearing is correct so that when I go up hills and such I don't bog down in second and have to drop to first and go up the hills with no speed.


That’s what the calculator is for. It gives you the speed for every gear and at what rpm the motor is at. Not just your top speed. It will show you the deference that just one change will make. Use it or don’t use it, it’s up to you. No one will be able to just give you the magic combo that you’re looking for. The tire size witch you don’t specify and the front and rear sprocket all work together to give you what you want. Not everyone likes the same power curve.

[JOHNDOE83]

you want 13/39 gearing