Intake/Exhaust Mods, Airbox, and Jetting

[Pladeaux]

Hello Fellas,
I ride another brand Quad, but My Best Ridin Bud rides the 400ex.
I am alot more mechanically capable and set with a workshop.
This is the situation. He bought a WB E series slip-on and installed it and uses their RevBox as well. He never did any intake mods or Jetting. Now he has the K&N Filter and Wants to run with the Lid Off. I told him he will have to now pay more attn to his maitenance and he has promised to do so. He wants me to do the jetting and install the K&N. At this point i have all the plastic off and the airbox out and cleaned up and the snorkle removed and the Hole blocked off nicely.
I read a great post here on how to go about removing the Choke and have decided that too will have to go at this time.
My question is, do I have decent ballpark figures on the Jetting for this set-up and Mostly Sea Level riding, 42pilot, 2-2.5 turns on the fuel/air screw, Needle on the 3rd or 4th clip and a 155 main jet. Opinions please and thank you.

[Pladeaux]

Hard to believe no one touched this. Well, I did the whole job and it turned out perfect. Jetting is very close if not spot on. I used the 42 pilot from my YFZ450 and the stock main jet as well (158), took out the Choke assembly and We fired it up the first time. By the way the Pilot I used was of the "Longer" variety. I didnt see any different in the business end of the Pilots, stocker-vs-replacement, so I tried it and it worked flawless.
Now he took his Red one back and gave me his Yellow EX400 and asked me to do the same thing.
Thanks for the "Pinned" choke removal post. Helped alot.

[zephead400ex]

:huh I was not aware that a YFZ450 jet would work in a 400ex....:confused:

I guess if it's working....:eek2:

[Pladeaux]

Yeah the mains are exactly the same. The 42 Pilot out of my Keihin was about 3/16ths of an inch longer that the 38 stocker from the Honda but looking at the way it sits inside the metal housing that sits down in the float bowl I couldnt see any logical reason that it wouldnt work. Well it worked and works well ;)