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Fuel overflow while running on 2006 Bayou 250

583 Views 16 Replies 3 Participants Last post by  WFO-KZ
What does it mean when fuel leaks out through here when running?
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It means the fuel shutoff device within the float bowl is not functioning. You need to clean or replace your float valve.
Also check floats to make sure they still float properly. If they leak and start filling with gas they get heavy and won't shut off the fuel supply.

Check to make sure gasoline has not made its way into your engine oil.
Usually the fuel will come out of a different one when the float won’t close. I’ve never seen it come out of the top one and only while running.
To be honest, the only reason I can think it is dumping extra fuel out of the carb while running is that it is getting way too much fuel , and has to jettison it. almost like a return on most 2 strokes.
Also , since this is a new carb, the only adjustment I can think of is the air/fuel mix or the needle valve clip so which of the two would be more prone to causing this?
I would start by measuring the fuel service level with the carb still in place.

1) Does it use a vacuum petcock?

2) Does it have a fuel pump?

3) Is this by any chance a third party carb made in China?
no, no, and probably (what isn't made in China these days?)
This is on a Kawasaki Bayou 250 from 2006.
If you have the old OEM carb, it may pay to rebuild it and keep the Chinese one as a backup.

Not knowing the jet sizes or needle settings or internal design of the Chinese carb makes it hard to speculate on causes. If this problem started from the moment the new carb was installed then you know the source of the problem but not the reason.

It would be worth taking the carb apart and testing float valves etc and noting the jet sizes and needle settings. Was there any other work done on your Bayou that may be relevant?
I had another thread the other day of all the things I done, it was extensive. I do have the OEM , might run it through the ultrasonic cleaner and give it a try. I really was just trying to understand what that port itself does (obviously it's an overflow) its there for a reason and would like to know it design purpose. Knowing that would clue me in on why it is overflowing.
Running fuel overflow has several causes. Clogged gasoline filters block fuel flow. A blocked or defective fuel pump could send too much fuel through the system. Cracked or leaking fuel lines may be a third cause. Finally, a faulty fuel pressure regulator could overfill the engine.
So I opened the Air/ Fuel screw from 1.5 to 2.5 and it helped immensely. It still bogs a lot once heated but it no longer dumps fuel
There is a fundamental problem here. The float stops the gas from getting in. Either it is a leaking float, which means it is full of gas, and is not floating (and yes, I've seen new ones like that) or the needle valve is not seated properly, or the float bowl is pointed straight up (exaggeration), allowing gas to come in all the time. It's easy to check the float. Drop the float bowl, the lift it till the gas stops. If it is high up, then lower the float using the adjustment tab. If it continues letting gas through regardless, your Needle Valve, and Seat are shot, and if they aren't removable, the carb is shot. Now, if you really know what you are doing, you can reseal the needle valve seat by making a tool with the proper angle, and hand form a new seat, and if the needle valve doesn't have any groves in it, you can just use that again. Some used to use O-rings as the seats which you would replace.

Anything outside of what I posted is not how carburetors work. They are simple devices, especially these kind.

Splitting threads is the worse thing you can do. It makes one not want to post in it, as it's too much trouble to follow.
I adjusted the air/fuel screw mix out to 2.5 turns from 1.5 and it no longer over flows. It was as I suspected.
Too confusing to folow. You posted earlier that the bike burped at that moment. Air screw adjustments set a ration, they do not control gas level. This makes no sense, and without pictures, makes even less sense. What you are doing is dumping more gas into the engine, but that screw in every carburetor I have ever see does not control fuel level. Adieu to you, the best of luck. I'm bailing! :)
I've been trying to tell you guys that outlet has zero to do with the float height. The float height overflow comes out a different hole.
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