Does Anyone Know Anything About A 400ex Carb?

[derekhonda]

My friend's 400 ex carbs pours gas out the overflow line. I took the carb apart, sprayed a bunch of carb cleaner on the floats and where they mount up to rest of the carburator (because i thought maybe the floats were just sticking) and it did nothing. Any other things to try? The bowl and floats did have a lot of small pieces of dust dirt in them, but i cleaned it out real good and it is still doing it. What else is there to try?

Thanks

Derek

[Toadz400]

The same thing happened to one of my Banshee carbs. Basically we cleaned it out a bunch of times, but it ended up working fine after just tapping the bowl with a screwdriver...hope that helps...:confused: :p

[Aallron]

Anything that will hold the fuel inlet needle off of the seat will allow gas to flow into the bowl and out the overflow... how did the dirt get in the gas tank in the first place ... second, no filter on the inlet to the carb ?

[cals400ex]

what year is the carb? in 2001 they revised the carbs and these newer ones don't seem to have the problem anymore. however, i think the older ones mainly had the problems when going up hills or riding wheelies.

[hondarider2006]

I have a 2000, and at like 1/4 the throttle seems to be like its at WFO unless you press hard, than it kinda pops and you have the rest of your thottle. I believe the older 300ex's and 99-00 400's did this. Now its fixed.

[derekhonda]

It is an 02. I have no idea why it was doing it, but there was dirt in the bowl so i figured it had made the floats stick down, thus continuing filling the bowl with gas (because the floats where down) and made the gas go out the overflow. Tell me more Aallron, i dont understand exactly what your saying.

[mbiigambler]

The fuel screw you use to drain to the bowl, there is probably a piece of dirt in there preventing the screw from seating fully allowing gas to still flow out.

Remove that screw and clean the end of the screw, or you can loosen it up and try retightening the screw.

[BSTURDIVANT]

You will have to remove float needle and blow compressed air thru both directions, probably has dirt holding needle open! Blow up thru seat (with fuel line off) and down the fuel line.

[wilkin250r]

Ok, here's the long version.

Your gas tank sits higher than your carburetor, right? So, the gas wants to flow from higher to lower, which means it wants to completely drain into your carb. This would obviously cause your carb to overflow, unless there was some way to shut off the flow of gas once your carb is full. This is where the floats come in.

Your floats sit inside the float bowl, and are attached to a little float valve (or some call it a needle valve, but its not the same as your slide needle used in jetting your carb). The gas comes pouring into your carb, filling the float bowl. This causes the floats to rise. When the floats rise, it pushes that little float valve closed, which shuts off the flow of gas.

So, something is causing that float valve to stay open. Either your floats are sticking and they don't rise, or your float valve is sticking and won't close, or there is dirt or something in the way that is preventing that float valve from closing all the way.

In any situation, the remedy is the same. A complete carb cleaning and rebuild. Get a can of carb cleaner and take your carb apart (follow the repair manual). Spray the carb cleaner through every single passage in that entire carb, both ways. The carb cleaner is cheap, go ahead and use the whole can. Clean out the float bowl, jets, idle fuel screw passage, intake fuel passage, accelerator pump, EVERYTHING.

Re-assemble, and the problem should be gone. I'd recommend an inline fuel filter with the re-installation, even before you test drive it. If you have dirt in your carb, you have dirt in your tank, and even testing your new carb for two seconds can introduce new dirt into your carb.

[derekhonda]

well i broke it back down tonight, pulled the whole thing apart, cleaned it all, put it back together, didnt leak.....for about a minute.

When the engine is on, it uses the gas quick enough for the gas not to over flow out to "over flow" But if you kill the engine, and leave the gas on, it starts to dribble out (but it is much slower)

SHould i do it again? Anything else to check?

[Sc0]

Replace the Needle and seat.

[cals400ex]

i have a stock needle and clip brand new, never used if your interested.

[derekhonda]

is that for sure what it needs?

[cals400ex]

i can't promise you that is what it needs. however, i have been told before that replacing these did make a difference. i am not sure why but i guess a bent or worn clip can raise or lower the needle a little bit and also make the needle not sit fully vertical.

[derekhonda]

how much??

[cals400ex]

i will give the needle and clip to you for $10 shipped. i paid over $30 for it. it comes with another jet that i needed and that is the only way to buy it. if your interested, let me know. thanks cal

[skemp]

I run into this countless times at work, and it usually boils down to a few things. The float pin that the float pivots on is binding up; usually caused from dirt or varnish. This can be remedied by taking the float pin out and cleaning it and the inside of the tab that it goes through on the float. Another common problem is once again dirt or varnish in the seat that the float valve sits inside. This can keep the rubber tip on the valve from fully or evenly seating into the brass seat, as well as hanging up the valve so that it does not move freely. Once again, clean the inside of the brass seat, as well as the sides of the float valve. This brings me to the other usual cause. The rubber tip on the valve can become worn or dried out meaning it is no longer a perfect 45 degree angle but rather a radius. This will also not give a good enough seal to hold back all that fuel. If the rubber tip on the valve looks good and the seat is clean, one thing that we do to freshen up the valve to seat mating surface is to get a drill bit around 3/16" and twist it BY HAND CCW lightly touching the surface of the seat. You aren't milling away material here, but rather cleaning away any imperfections in the seating area and exposing clean brass.

Hopefully this will help you fix the problem. I tried to make it easy to understand, but the way I think is certainly different than the way you think. It should give you the basic idea though. Good luck!

[derekhonda]

Well, I have cleaned it out number times, but the last time i physically took out the float pin, the floats, and the thing that looks like a rocket and blew compressed air and carb cleaner all throughout all of them. It managed to slow the leak, but it still does leak. Ill try one more time and see if i can get rid of it, if not ill try your deal cals.

Thanks everyone

Derek

[wilkin250r]

Did you get the fuel filter? I had the same problem on a little 250X, and the ultimate problem turned out to be dirt in my tank. I'd rebuild the carb, it would work fine for a little while, and then begin to leak again because I got more dirt in there.

There's no point in cleaning your carb if you're just going to get more dirt in there. And if you have dirt in your carb at all, then trust me, there IS dirt in your tank. That's the only way it could get into the carb.