400ex will not run at idle

[columbia7200]

I have a 2000 400 ex that has been setting up for several months. I can get it started and running, however when the engine heats up and I turn the choke off it will go dead. As long as the RPM's stay up it will run. The engine is still very responsive, and runs great, just it won't idle at all. I've have adjusted the idler screw, throttle cable tension, nothing seems to work. I think it is a problem with the carburator, but I am no mechanic and don't know anything about carbs. Also when I am riding with the choke off, the engine will backfire alot when I let off the throttle. Is this a carb problem? How much would it cost to fix? Please I need help fast!! Thanks.

[quadrider400]

You have no sig listed so this a stock bike?

However based on what you have listed try the following:
1. Replace the plug and make sure it is gapped correct.
2. If you have not for a while..... clean the air filter.
3. If you have a Whites Bros. (p.o.s.) CDI try putting your stock one back on.
4. If you have had the carb apart I would double check that everything is where it should be as the idle adjust screw if rotated clockwise should increase your idle pretty well no matter what.
5. Look for any worn wiring that might be making contact and allowing the bike to short out.

Let me know how ya do after this..... :confused:
Quadrider400

[columbia7200]

Yes this is a stock bike. Sorry no sig, I'm a new user to the board. Anyway, I've replace the spark plug, the airfilter is clean, no electrical problems detected. I drained the fuel tank and put fresh gas and some carb cleaner in it. This seems to have resolved part of the problem so far. Anyway thanks for the suggestions.

[EXerHonda400]

okay, just throwing something out on the table, but mine also did something that sounds a lot like that. And just by a fluke i turned the valve on the gas tank to reserve and it ran 100%, but also you should maybe put a bigger pilot jet in even though it is stock but if it used to run fine then that wouldn't be your problem. It always helps to eliminate problems so start at the beginning, take the hose off of the tank that goes to the carb and see if it is flowing fast and freely, if it isn't take the valve off and check to see if the filter is dirty. then move onto the carb, take it off flip it over take off the bowl then take out both of the jets (main and pilot) and make sure they are clean. then make sure also that the hose that goes into the carb from the tank is free of any obstructions.If you don't eliminate it as a problem then the potential is always there, but the first thing i would do is turn it to reserve, and if it works in reserve then your filter is probly dirty.

[columbia7200]

Sweet idea and thanks for the tips, I haven't touched it since last tuesday since It's at a friends house. But i'm going riding today, so I'll try those tips.

[columbia7200]

Well I got my little problem fixed. I pulled the carb off and took it apart. Apparenty the jets were really clogged, so we cleaned them up and put it all back together, runs like a new one now. Thanks for all the advice.

[seven]

Clean your carb and jets!

[EXerHonda400]

no problem anytime

[djsblaster]

Hay from the sounds of it may be the flots could be stuck so it is flooding it when it is idaling but im not to shure thates just a possibility. it would leak a little gas if it was.on my trx90 i had the same problem and i sat and did the jets and cleaned the carb but i couldnt figure it out but then i finaly got some carb gaskets to seal up vacume leak and that was the reson it wouldnt idle.

djsblaster:confused:

[dirtmomma]

Originally posted by djsblaster
Hay from the sounds of it may be the floats could be stuck so it is flooding it when it is idaling but im not to sure thats just a possibility. it would leak a little gas if it was.on my trx90 i had the same problem and i sat and did the jets and cleaned the carb but i couldnt figure it out but then i finally got some carb gaskets to seal up vaccum leak and that was the reason it wouldnt idle.

djsblaster:confused: