Ok, everyone is saying that the 2000 400ex has a problem with the throttle adjusted from the factory incorrectly. If anyone has experienced this, please tell me exactly how to check this and fix it. I would be absolutely thrilled to death if my new stock 400ex had even more power than it has now. Please respond the best you can. I know that it is difficult to explain some things without pictures or in person, but try.
Thank you very much.

 

take the tube out that connects the air box to the carb, just take the band clamps off the ends and presto.now look into the carb, at the same time slowly press the throttle to wide open position. the cylinder thing in the middle of the carb, you notice it's the only part that moves, should go up and you should only see a tiny bit of it if at all. put the boot back in place between the carb and airbox. if you see more, start it up, and slide back the little boot thing that connects the cable to the thumb throttle piece. and adjust it out till there is little play left in the system. retighten the loock nut and get ready to ride. it shouldn't idle faster, thats why you started it up.

 

What he said.

 

Mine seemed to be fine. I looked at it and then brought it to the dealer. After drawing blood, they finally came out to look and say that it was fine and that the internet rumors are $@#^#$. and that Honda would not do such a thing. thanks for the help.

New question. Has anyone put on a different air filter and cut any holes in the lid and rejet the main without doing a pipe? I know everything about the Warrior, but this Honda is Chinese to me. I copied success last time and loved it. I put a mild cam and 10.25 to 1 piston in the Warrior along with air box mods and larger main. Then I bought a White Bros E series pipe later. I do not want the 400 loud like the Warrior was, so I want to know what I can do without losing the pipe. Would love to put the bike on a few pound diet but don't want the noise. Thanks.

 

I put a Uni Filter on mine and upped the main jet 2 sizes and it is a noticeable improvement. No holes, no pipe.

Thing runs great. (And quiet).

RM

 

i just bought a new 400ex and had the same problem and i know a few oeople that have also had the same problem

 

Same problem here. The dead give away was the throttle adjusting screw was screwed in all the way. I adjusted it according to the manual and it helped alot.

MARK
00 400EX

 

Just as a footnote to the above comments on throttle play adjustment on any quad or bike; they are normally adjusted, if not installed, by the dealer after unloading from the crate at the dealer's shop, and usually not too precisely.
The "cylinder thing" mentioned by someone is called a slide, strangely enough, since it slides up & down in the carb body. It also contains the needle jet.
the proper adjustment of the throttle cable is to remove all but the slightest play in the cable with the adjuster and BEFORE RIDING!, start the machine & at idle, turn the bars full lock in both directions. If the idle increases, back off slightly on the adjuster until idle remains the same from full lock to full lock. Too tight an adjustment can cause an unwanted speed increase in turns & a potential accident.

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THE AZ HARD PACKER, calmiller@kachina.net

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