Hey All,

I have a 2001 Honda 400EX.

I am having 2 problems.

1. It wont idle.

2. In the summer when it was idleing, it would dump fuel out of the overflow.


My Guess is that in order to get it to idle, we had the idle up soo high it was flooding the Carb, and thus overflowing... I could be wrong, but it's the only thing i can think.


How many turns out should the idle screw be?

Could valves needing to be adjusted cause idle problems?

Does anyone have a walkthrew for how to check and adjust the valves on the 400ex?

What other suggestions do you guys have as to why it wont idle, and why it the carb is overflowing? (I did take the float bowl apart and checked the floats, they are free moving, and there is nothing in the float bowl that would cause it to stick.)

Thanks,

-ThaChad

 

Take the floats out and check the needle and seat. If there is debris in there the needle won't close all the way. Also check the vent tubes, make sure they are not stopped up. The "idle" screw or the "mixture" screw????
You can check the seal on the needle and seat by removing the float bowl, connecting the fuel line to the carb, turn the gas on and push up gently on the floats. If gas continues to flow, there is the problem.

 

The "Idle" Screw.


I checked the float bowl before, and the float was free moving. I can take it all apart and check it again... But I want to get it to idle correctly, first.


Thanks,

-ThaChad

 

Turning the idle screw in won't "flood" the carb. When you take the bowl off it's not to check the free movement of the floats, it's to make sure the needle and seat are sealing properly.
It can only be a couple things. The needle and seat are not sealing when the bowl is full of gas allowing gas to flow constantly, one of the vent tubes is clogged, or the fuel level is too high.
If it has been leaking, it would be a good idea to check the oil, it could have gas in it. Check the air filter to. There may be gas in the airbox.

 

Soneone before had told me that if the idle is too high, it can cause the float bowl to over flow... So that is what I was going by.

I'll have to take it apart and check as you have suggected..


Any suggestion as to why it wont idle? and how many turns out the idle screw usually is?

Thanks,

-ThaChad

 

first figure out why the carb is leaking. Then turn the "idle" screw all the way out. Start your quad and manipulate the throttle so it won't die. Give the idle screw a couple turns in and let off the gas. If it dies give the screw another half turn or so and start the machine again. Repeat untill the machine will idle.
Do you know how to adjust the mixture screw????? Not too difficult and it will achieve the best mixture for the best throttle responce off of idle.

 

Just to confirm. You said turn the Idle screw all the way OUT? So that would be turning it to the LEFT untill it stops?


What should the mixture screw be set at? When I take off the float bowl, I can adjust the mixture screw too...

Thanks,

-ThaChad

 

yes turn the screw counter clockwise. The mixture screw should be adjusted while the machine is warmed up and running.

 

When I do this test, If it continues to flow, what will the next step Be?

Thanks,

-ThaChad

 

The float/needle/seat are designed to maintain a predetermined level of fuel in the carb bowl at all times. It does't matter what position that the throttle is in. (As long as everything is working properly.)

You stated: "In the summer when it was idleing, it would dump fuel out of the overflow."

I would suggest that the vibrations of the engine running, caused the needle/seat to allow too much fuel to be delivered to the bowl (thereby causing it to have a bad idle). By checking the operation of the float with the carb disassembled, you MAY not find an obvious problem.

Try this: Turn engine off. Disconnect fuel line at tank petcock. Blow into fuel line while lightly tapping the handle end of a screwdriver on the carb bowl. If you can blow through the fuel line, the float/needle/seat are not working properly.

If this situation is corrected, you may not have to do any further adjustments. (Wouldn't that be nice!)