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400ex fuel leak issues


oldschoolsdime92

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I have an 2002 400ex, with more time sitting than riding on it.

I am having a carb issue. My overflow tube on the carb bowl continually runs fuel. When I put the petcock in the off position, fuel still runs. I assume the petcock is faulty there. My real concern is the carb dripping fuel all the time. I replaced the o ring on the bowl drain screw, and I am assuming im having float issues. Either the float height isn't right, the float is sticking or the needle isn't seating. Can anyone else give me any insight? Aside from these issues, the bike runs great, idles good, has great power.

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Probably will find corrosion on the needle and seat. Check the float and the float level. Float movement (with needle) should be smooth and free.

Fix the fuel shut off valve. The carb isn't really meant to prevent fuel leaks, the shut off valve does that.

This is important, since some fuel leaks out the overflow, and some makes it into the cylinder, past the rings, and into the crankcase. Easy to tell if it's happening, you can smell fuel in the oil. You don't want that to happen.

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im certainly going to fix the shut off valve, its a huge annoyance, especially removing the tank. It never leaked until I put a full tank of fuel in. But i figured I would kill two birds with one stone while I had it apart. The carb issue is what was baffling me more than anything.

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supposedly , per the service manual, the float is non adjustable, and you just replace it. I'm not understanding how you can have a float thats non adjustable, but i guess its possible.

It's pre adjusted from the factory. The new Holley four barrel does that now.

edit: floats sticking are a bit common. Especially after work where the float bowl had no fuel.

Sometimes it takes a little fiddling to get the float to start acting correctly.

Typically I'd hit the side of the float bowl with the butt of a screw driver to knock it loose/free.

Edited by ReconRat
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Inspect the float needle closely. If the rubber tip has hardened at all or has any metal buildup it will not seal. Also if it's older sometimes it will look like there is a ridge on the needle, if that's the case you need a new needle.

I always used carb cleaner and took a fair amount of time to polish the needle tip. As recon said the seat needs be be shiny and clean with no build up at all either.

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Pulled the carb back off, and spent quite a bit of time in there on the seat scrubbing with carb cleaner and a Q tip. I was really surprised at the amount of crap that polished off the seat. The drip issue is solved. Now I must move onto the petcock issue of not shutting off. I think im just going to replace that.

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