rejetting my 2001 400EX

[cesar3815]

I live in Las Vegas Nevda and I bout some jets but do not know where to get the installed. Could you help me out?

[400exrider707]

Does your 400 even have any mods? If you have a stock quad and bought a jet kit your basically wasting your time.

[cesar3815]

Yes, i have and after market exhaust and k&N filter!

[2004exrider]

try it yourself, its fairly simple to do. Just get a 17mm socket and take the cap off the bottom of your carb, then get a 6mm socket and thread out your main jet. If its keihin jets, then try a k165 i believe thats going to be a little on the rich side and work your way down or up depending on how it runs and how the spark plug color looks. If its dyno jet, try maybe a 155? not really to sure. but either way its going to be cheaper to do it yourself.

Jimmy

[04TRX400EX]

Just put a Dr. D slip-on and a K&N on my '04 400EX and went from a 148 main to a 150 main and it runs great. It's really easy to do yourself, give it a try!

[04TRX400EX]

Forgot to add: pull out the spark plug after you rejet it to see what color it is. It should be a nice brown/tan color. Dark brown or blackish is too rich, white is too lean. Use the spark plug socket that came with the quad to remove it. If you don't know, the spark plug is located in on the front of the head in the center. Pull off the yellow/orange plug wire first :)

[ccd]

Here is a link to a list of jetting specs I compiled from this site: http://www.dunbarphotographic.com/400ex%20jet.htm

I punched out the factory muffler and installed a uni-filter. Installed a 155 main jet,stock pilot, 2 1/2 turns out on the screw= Tan plug. Perfect. The elevations I ride are between 500-4000 ft. Mass and VT.;)