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rYan01400EX
07-07-2006, 09:21 PM
Alright, to all of you who can help.

On my 400EX, it will run fine until in higher RPM's. When it reaches these, it bogs out and acts like it's maxxed out. It's NEVER done this before.. So I thought it was a 180 degrees out of time.. Wrong. I checked it for the 6th time today. Also, it's not the rev limiter because it has NEVER in it's entirety, hit the rev limiter. I'm leaning towards a carb. problem? What do you all think??
†2005 400ex†
07-07-2006, 10:10 PM
thats all i can think about it being...Have you moved recently or were you riding in higher than normal elavations?
rYan01400EX
07-07-2006, 10:12 PM
No sir, everything is the same. It just started acting up.
GPracer2500
07-07-2006, 11:18 PM
Main jets have been known to loosen and fall out. Needle clips have been known to break too. I suppose it could be an ignition problem--hard to say from your description--but I'd remove, inspect, and clean the carb first. At the very least you can eliminate that as the problem.
rudabaugh
07-08-2006, 08:45 AM
This may sound elementary, but I had the exact same problem with my 400 that I just bought. Then just as I was about to tear apart the carb, I noticed that the intake pipe looked a little off. Sure enough it was sitting half off the carb. Resecured it and she runs great now.

Bottom line, check for anywhere that additional air might be getting sucked in.
JPhonda
07-08-2006, 09:19 AM
mine did that when my main jet fell out. just check your main jet it only takes a couple of min
rYan01400EX
07-08-2006, 09:47 AM
Alright, I'm new to whole carburator thing.. I am mechanically inclined so could someone tell me where the main jet is?
rudabaugh
07-08-2006, 03:00 PM
The main jet is located on the underside of the carb. There is a 17mm? that has to be removed to reveal the jet.

This may help -

Jetting Explanation - http://www.exriders.com/techarticles/jetting.html

400ex tear down -
http://hondaex.com/techtips/jettingguide.htm

Actual Pics -
http://www.dynojet.com/pdf/Q107.pdf
Wildbrain
07-09-2006, 01:37 PM
Same thing happened to mine. I took off the carb and didn't really see any dirt or anything,so I put it back on, it ran OK for alittle while now I am having problems again.
Next I am going to clean the entire fuel system to see if that will maybe help.:confused:
rYan01400EX
07-09-2006, 02:19 PM
I think I may run SeaFoam through mine. It worked in my truck, we can sure try it on the quad.
Wildbrain
07-10-2006, 04:20 PM
bump