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View Full Version : 400ex Running Strange



ouhockeyplayer
03-09-2007, 08:31 AM
First off I would like to say that I am brand new to this board and look forward to using everyones wealth of knowledge on the subject. Ok here is the problem. I have a 2004 400ex that I bought as a left over two summers ago. It has always been difficult to start from day one and never liked to idle. (My dealer did a horrible job on prepping it) Well I can never leave anything alone, so I decided to add a Dubach Racing slip on and K&N air filter to it. I also added a rev box too. I've done many other mods too but that is the extent of the go fast stuff. After the mods it would not idle at all, and I had to constantly be on the gas. It would backfire and sputter while I did this. I adjusted the idle all the way seeing the idle was week but it had little effect. So I then had the dealer rejet the carb and it ran fine after that, but the idle is still almost all the way up and not overly quick like it should be. Well now the problem is back again and when I go to warm it up the header pipe glows red. I took the spark plug out and it is black in color. I don't remember what size main jet was replaced at the dealers, but I think that is all they changed after calling Dubach Racing. The weather in Michigan is pretty cold right now, and I am sure that is having some effect. PLEASE HELP, I want to ride..

Eviltanker
03-09-2007, 08:48 AM
Put your needle on the 3rd clip, screw at 2 1/4 main start with a 155 pilot go with a 42(all Keihin) that should get you on the right track.Once you put in the 42 adjust your fuel screw to the 2 1/4 to 2 1/2 point from lightly seated. After you do all that get some extra new plugs and start doing plug chops to see where you stand at each area (closed to 1/4, 1/4 to3/4, 3/4 to WOT) that will tell you which way you gotta go from there. Anybody else chime in if I missed something. You might want to go to www.jetsrus.com and order some extra jets (42 pilot, and 155 through 170 mains)

ouhockeyplayer
03-09-2007, 10:02 AM
Thank You. That was a quick reply. I will give it a try and see what happens. I will have to post some pictures soon of my EX. I'm pretty proud of it just like many owners are on this site.

woodyzr2
03-09-2007, 02:58 PM
Ortonville? Might have to hit the Mounds this summer!

Good luck with your jetting...try asking Colby what jets you should go with, he got mine pretty much spot on.

ouhockeyplayer
03-10-2007, 02:37 PM
Here are some pics of my EX

ouhockeyplayer
03-10-2007, 02:37 PM
other side

woodyzr2
03-10-2007, 05:01 PM
wow...I wish for the day mine could be that clean :eek2: