K&N Jet Kit Stage1&2

Has anyone done the k&n jet kit for their 400ex? I just threw on my WB slip on and k&n filter but kinda hesitant to do the jetting myself. If anyone has, could you give me a walk through on how to? Any help would be appreciated!

[Braff1]

Ogre helped me rejet my 300 Ex here a while back. Below is how he recommends you to rejet. It may seem a little strange but it does work.


"Jetting can be very difficult given the way you're approaching it. Plug reading has become unreliable given newer gas additives and longer life plugs.

Another (and safer) way to jet your machine is to "over-jet" it. The point is to make your machine run too rich - it'll give you a reference point.

First, you have to test if your machine is already running rich (with the 180 in it).

Put the machine in 2nd gear, get rolling enough so the machine isn't quite lugging, then roll on the throttle. Hold it wide open til it either (A) skips, blubbers, cuts out (can't miss it) OR (B) you've reached the top of the revs without the above symtoms occuring.

If you get A, then you're too rich on the main.

Else, if you get B, then run to your dealership and pick up a 182, 185, 188, 190. Retest with the 190 in. If you get A, drop to a 188 and retest.

Continue to do this until you achieve B. Then, drop back one more - you should be perfect then.

If 190 isn't high enough, go get more!

Although 180 does appear a bit high, only YOUR machine knows what it wants.

This is basically a fail-safe method, you will see results.

What to do with all the extra jets? Just return them, most dealers are happy to take back the unneeded sizes. Or if you're like me, you'll keep em, never know when the next engine mod will come along!

I've performed this jetting technique countless times - it is much easier and more effective. Plus, you won't have to burn your fingers trying to get the darn plug out!


Hope this helps,
ogre"

Cool info...thanks! I was really looking for some exact steps for a 400ex... the instructions for the kit have the tuning and troubleshooting. Do I need to take the gas tank off to get to the carb? Should I turn the gas off to drain the carb first? and so on...

[Braff1]

If you are replacing the needle with the dyno jet needle than yes you will have to remove the gas tank to get to the top of the carb. The instructions should be pretty clear on putting the new needle valve in and where to place your clip. If you take the tank off you might want to pull the carb off, turn it upside down and remove the bottom of carb (the 17 mm hex head bolt) this will give you access to your main jet without removing the whole float bowl. After removing the main jet replace it with the adaptor that comes with your kit and the recommed main jet for what mods you may have along with your altitudu. If you are not removing your stock needle valve then just remove the 17 mm hex head and go from there. Replace in the reverse order you took everything off and you should be ready to fire it up.

Thanks Braff1.... thats the stuff I needed to know!

[Drtridr18]

so just to be safe, it's easier to just remove the carb from the boots and do all the stuff to it that way?

i'm doing a K&N kit too, Yohsi. slip on with stock airbox lid, in northern ohio climate

any help is appreciated, thanks

yeah.... do the needle first by taking the top plate off and then reassembel. Then pull the carb out of the boots and turn over to do the jets... I didnt have to disconnect the throttle cable to do so. here is a little step by step:

1. remove seat, tank cover and gas tank(turn fuel valve off and take hose off too)
2.remove plate on top of carb to get to needle and then replace
3. disconnect from intake outtake boots and turn over(use a rag while turning over, access gas leaks)
4. remove mainjet cover and replace when finished.
5. work backwards from there

[Drtridr18]

Hey thanks for the help