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Tim_Whisnant

'98 YZ400 carb leaking gas

7 posts in this topic

I went to clean out the carb because it was running real bad at 1/4 throttle and when I put it back on and turned on the gas, it started dripping fast out of the black hose towards the bottom. So I took the carb off again and checked the floats and everything looked OK. Put it back on again, turned on the gas, and the same thing happened !! :)

I didn't adjust anything when I had the carb opened, just blew out the jets and put everthing back together. Anyone have any suggestions ????? :)

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I believe there is a bowl drain on this carb, but I'm not sure.

If the leakage is from coming from a fitting on the bottom of the carb this is the overflow, but also the bowl drain, if so equipped it is shut off via a transverse screw in the bottom of the bowl.

If this isn't it have you checked to see if the needle valve isn't leaking? With the carb off the bike and bowl off the carb you can operate the bowl to ensure that it is shutting off flow completely.

Hope this helps.

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Yeah i would check the drain allen screw on the side at the bottom of the bowl. Its a gold allen type screw :)

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Thanks for that info, I'll give it a try. If it is the screw though, would it be leaking out the bottom tube like it does ? Or where the screw goes into the bowl ? :)

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Its the float shut off mechisim. that little tab has been bent down (most likely) and isant stutting it off all the way. This happend to my friends 125. Simple fix. Just make sure not to bend it too far or else it'll starve the engine of fuel.

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Thanks for that info, I'll give it a try. If it is the screw though, would it be leaking out the bottom tube like it does ? Or where the screw goes into the bowl ? :)

This screw blocks off a passage at the bottom of the bowl overflow, so if you back it out the bowl drains out of the overflow tube (not out of the side of the bowl where the screw is).

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sounds like u have a worn float needle valve,,,,,,,,ive had similar probs in my shop where after carb clean needle valve dries up then wont seal thus causing to much fuel to enter the carb (no matter if float height is proper or not). if float bowl needle valve rubber tip is old it will leak! cost about $25 and is a dealer part.(atleast ive foung no aftermarket for the yz's

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