running 162 main on stock engine????

[ridinthedunes]

My 400 was always faster than my wifes (both are stock with
K&N), I never thought much of it until I went riding with a buddy
of mine who had just got a 400 and installed a K&N and my quad
was faster than his (we switched so I know it is actually faster).
I checked my main jet and it was a 162!!! I installed a 162 in my
wifes and it ran great! I think it had a 142 in it (though I'm not sure). My buddy put a 162 in his and said
it was a huge difference. Both quads start, idle, and run great.
I did it while at sand lake on the oregon coast.

Doesn't this sound WAY to fat for stock???
Does anyone have any ideas on why it seems to work
so well.

(I checked the plug and it seemed a little fat...but not
much)

Thanks,
R/T

[tprender]

The 148 is stock on the 400. Most people find that around 155 is best on the stock engine. If you take 2 of the same of any bike or quad, you will find that one will be a little faster than the other. Also, remember that from the factory they are jetted on the lean side. If you change the pilot to a 42 or 45 it will run just a little best. It will also make it start much better. Take the airbox lid off and see the difference it will make. Type of gas and how old the gas makes a big difference. What about size of tires?

[ridinthedunes]

I have the airbox lid "slightly open". I am running 20/10/8 I
think. I'll try changing the pilot....guess I'll have to get the
book out.
Thanks for the info.
R/T