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brand new float still sticking?? I'm stumped--help

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Short history: bought '96 xr400 recently, some mods, never rebuilt. the float was very tempermental (stock carb). It would stick and the overflow would leak uncontrollably. I had to bang on the float bowl to get it to stop, or shut the gas off, and drain the bowl. I cleaned (carb cleaner/toothbrush/etc) and reassembled it twice, and it actually got worse. 😢 So, I decided to order a new float. Installed it to specs(14-15mm), cleaned again, and reassembled.

This time I took it out, I got it off the truck, turned the gas on, and it was overflowing. . . I drained the bowl, kicked it over, and turned the gas back on. no leaks, so off I go. everything was fine, hitting whoops, etc. then, out of the blue, I loose about 20% power, and the bike gargles like it is flooded, I looked down, and drip drip drip. I shut the gas off, rode a little farther, jostled the float, and it stopped, so I turned the gas back on and continued. This happened 2 to 3 times in 30 miles.

I thought I had it fixed before I left, but I was so mad it was leaking again, I wasn't going to let it ruin my ride. I know the best solution is to just buy a new carb, Well, being the poor spode that I am, I can't afford one, so. . . Is getting a professional carb cleaning a waist of money, will it sove the problem, or is there some thing else going on??? help. 😢

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thanks,

I was very surprised the first time I cleaned the carb, as it was very clean and not rusted/corroded inside. I am not sure how to check if the needle is the culprit. when I installed the new float, I pushed it up and down to make sure it was shutting off the flow properly, and it was. the tank may have some crap in it though, I am definately going to interrupt the line with a small filter, after cleaning the tank, but I honestly don't think that is the problem.

what do you know about the "ultra sonic" vibrating cleaning machines for parts they have now--hoax or does it really work that well?

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With the float did you replace the needle and seat that the float attaches to? You may be thinking of the wrong needle. And are you sure the float is adjusted correctly? You may just have it set to a really high float level.

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The ultrasonic cleaners do work (with the right solvent),. When you pull the float needle and seat out, look (like with a magnifying glass) at the needle and see if it has a little "ring" worn into the sharp end where it contacts the seat. I've seen this on several carbs before, just happens over time with vibration I think. The fuel filter is a good idea, as gas prices go up, the dealers start buying from distributors they wouldn't have touched before. The stations also run their tanks lower hedging on the price when they have to get a load, which leads to the pumps picking up more water and garbage. 😢

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I did not replace the needle that the float attaches to (I asume you mean the little grooved, pill-sized shaft with a rubber nipple on the end of it, the other end has the wires attaching to the float.) I spoke with a shop that said that those simply don't go bad. when I looked at the rubber part, there was no wear/ring around it, so I put it back in. which direction do I re-adjust the float if that is indeed the problem?

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Just a thought - Make sure that the plastic "anti-slosh" tube thingy is installed correctly and not hanging up the float. It's a pain to get back into the carb if it's still on the bike because it get's loose and doesn't want to stay in position when you put the bowl back on. I've done the fuel tube replacement trick but I may sweat on a piece of brass tubing to replace it when I pull it apart to replace the choke plate.

Good Luck,

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is there a detailed schematic of the stock carb out there that someone has to help me out with this problem? I will check the anti-slosh thingy again, but how do I know if it is in wrong--it seems to fit only one way??

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I beg to differ with the guy you talked to, but the rubber cone on the end is what makes the seal when the float rises, and after a few years, they get an indentation in them and either don't seal reliably, or stick shut. That and the seat it goes into are only a couple of bucks, and are a very important part of the system.

Sorry Mar, didn't see your response, take this as a second on what Mar told you. Also, my bad, the seat isn't replaceable in this carb.

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I see some great posts here.

1. In-line fuel filter.

2. New float needle(the tip is rubber, and DOES wear out!).

3. Correct float height.

4. The little plastic thingy.

No reason to buy another carb. Fix the one you have, there isn't much else that can go wrong.

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The max float drop on this carb needs to be set too. From the factory it's like 25mm or more, too much. That allows the float to flop around in the bowl between minimum(14.5mm)and max settings, especially on rough/bumpy terrain and that causes fuel to be displaced up into the carb thru the main jet, causing the stumble and also out the overflow vent line. Set max drop, per the procedure shown in the manual, to 19mm.

Yes, the baffle thingy can only go on one way, as the little notch in it accepts the vent tube in it when installing the carb bowl.

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I've experienced your problem several times. 100% of the time it is that stupid plastic collar around the main COMBINED with having too much drop on the float. And this includes some REALLY old needle & seats

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thanks, you guys are really helpful, i was about to give up. . . one last question...I will find out how to set the max drop on the float, but I don't know how to make sure the plastic thingy stays put? do I makeshift a pinchy wire or something??

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As for the plastic baffle thingy, I heated mine in boiling water to soften it a little then remove it and while bending in the little arms that grip the jet tower, hold it that way and put it under cold water to "set" them there. It should grip the jet tower better then.

PM me with your email address and I'll send you a scanned file of the manual for setting the float.

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I took my slosh baffle out. No change in riding performance, whether its an MX track or the Whoop Capital of the World, Wambaw Cycle trails.

Maybe its just me?!?

Robert 😢

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Trailyrider's trick works. There are two little prongs that stick up from the top of the plastic slosh deflector. Warm those two prongs in hot water and gently pinch them to close down the slot between them. That slot rides on a rib of aluminum on the carb body where the main jet screws in. Narrowing the slot creates a bit of friction to hold the plastic slosh thing in place while you lift the bowl in place. The float as it drops likes to knock the plastic thing off Once the bowl is on it can't slide off.

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