I called the guy I bought it from and he said that everything was put on there together. He installed the stage two jet kit set-up, and set it up for our elevation and pipe and filter. I then went to the dyno-jet web site and seen that the stage two kit suggest that you run with the lid off. I then called their tech support and he said that the only way it would run correctly is to leave the lid off or jet it down. I am not sure what jet comb. is in it.But I don't really want to mess with the carb. The guy I bought it from said he set it up just like the one out of a nov.99 dirt wheels issue. If anyone has this issue and can fax or e-mail be a copy of the article it would be great. Last night I cleaned and oiled the filter. Hopefully that with the lid off will fix it. I also put the stock rev limiter back on so I could have some sort of bench mark. Hopefully it will quit raining today so I can test it. CJ

 

I have a 2000 Honda 400ex also and had a similiar problem as well. I also have a FMF Powercore 4 exhaust system and a kn filter with a dyno jet kit. However I do not a WB rev box. When I noticed that my quad would start to "boag-out" I first thought that it was a jetting problem. Unfortunately, I forgot what I set my main and pilot jetting because that was the first thing that came to my mind. As it turned out, I talked to a motorcycle mechanic that does a lot of work with 400ex's and he said to check the air box and clean it out really well. So I did and it solved my problem. I would suggest that you clean and oil you kn air filter very often. Especially if you go ride somewhere where there is a lot of dust, mud, or sand. Thank God it wasn't a jetting problem. I would have had to take my 400ex almost completely apart.

 

Fourtracker14 sounds like we have identical 400ex's. I rode it last night and the problem was fixed. Before it would drop the front end down when I shifted into 2nd, but now it carries it through the entire powerband. It's an all new bike to figure out. I think it was more the airbox lid being on than the dirty airfilter. The k&n wasn't that dirty at all, but I went ahead and cleaned it. Do you run yours wih the lid off? Do you have an outerwears on yours? How often do you clean your filter? Thanks for the input, CJ

 

CJ,

I run mine with the airbox lid on. But I also drilled a couple of holes in it to get a better air flow. I also made my own outerware. My friends mom went a store and bought the same kind of material and measured it to fit perfectly under the airbox lid. I don't think that the outerware made a difference at all. Besides that I have a precharger on my K and N air filter. I am glad that everything is working out better on your Honda. If you have and other questions, feel free to e-mail me anytime. My address is Fourtracker14@aol.com

 

You guys are making this harder than it has to be. You can take the whole carb off in less than ten minutes. All you have to take off to get it out are: rear fender/seat assembly and both black panels on the side of the tank. Once you get the black pieces off the tank it will pull up enough in the back to get the carb out. Tuning is as follows:
Pilot jet determines idle to 1/4 throttle.
Needle determines 1/4 to 3/4 throttle.
Main jet determines 3/4 to full throttle.