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2001 yz 250 carb problem

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So as soon as you turn the gas on gas spews out of the bowl overflow line on the bottom of the bowl. I checked the float, and its not stuck. I took it out and the jets and blew compressed air through. The guy i bought it from said the carb was rebuilt, im wondering if it has the wrong seat or float or something. Help!!!

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Make sure there arent any holes in the floats either. They can have a tiny hole that lets it fill up, then it wont float and starts to overflow. Happened on my old KX125.

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Check the float height, and make sure they move freely within binding.

If that does not cure it, Keihin Pwk's are notorious for leaking needle valve seats. There was a thread on this somewhere on TT. But all you need to do is wrap a piece of 400 grit sand paper around a drift punch so that it fits tightly in the seat and spin it around 2-3 times. That will remove any burrs in the seat that prevent the needle from properly seating.

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I am throwing my bet at float level and second the seat. the seat only gets nasty if the bike sat for a long time with contaminated fuel (water in gas). 

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I looked at the seat. The seat and the needle looked fine, the needle looked brand new. I guess i could check to see if the float actually floats but i disnt see anything. To adjuat the height and make the float shut thebfuel off do i bend thw tab up or down..

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The Kehin flat slide on my Harley overflows if I leave the fuel off for a long time,  A couple of strong raps on the float bowl sets things right again.

 

When you have your carb out again, put a hose on the fuel inlet and invert the carb and watch the float move through the cycle and see if the needle seats and what the float level looks like when it does.  Worth a shot.

 

I polish the seat with a few twists of steel wool, buffs it right up if you need to.

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I looked at the seat. The seat and the needle looked fine, the needle looked brand new. I guess i could check to see if the float actually floats but i disnt see anything. To adjuat the height and make the float shut thebfuel off do i bend thw tab up or down..

If the carb is in correct orientation then bend the tab up, very little.

Here is a way to check height without the tool. Put a new piece of hose on fuel inlet with carb off bike, bowel off carb, while blowing into the fuel line push the float up until it shuts your air flow. Rude, but it works.

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I would take the bowl off, remove the jets, then blow some air so that it blows OUT of the fuel line coming from the tank.

I put my other tank on my bike at a ride this spring and it started doing the same thing as yours. Turned out there had been a little dirt in the tank which then got down into the carb. Blowing air backwards thru the carb cleared it out. Caught the debris in a paper towel.

I've since bought a second fuel cap to keep both tanks capped all the time, and started running a fuel filter between tank and carb.

Took my carb apart about five times the weekend it happened trying to solve the problem, and a little compressed air is all I needed.

Edited by TN Dirt Rider
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The problem with pwk's is the needle getting stuck in the seat before it actually fully seats. The needle wears out the sides of the seat, not the bottom. If you pull the floats off, take the needle and try pulling it in and out of the seat. Try adding very light sideways force, it should bind and not fully seat.

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Fixed!!!!! The blowing air through method helped me figure out when it was shutting fuel off. All i had to do was bend the tab on the float up. Took three times to get it right on. After the second time fuel was just drooling out so i bent it up once more and bingo. Rode it hard for a minute seemed fine. Thanks for your help

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Fixed!!!!! The blowing air through method helped me figure out when it was shutting fuel off. All i had to do was bend the tab on the float up. Took three times to get it right on. After the second time fuel was just drooling out so i bent it up once more and bingo. Rode it hard for a minute seemed fine. Thanks for your help

 

Good to hear my madness of a method worked for you.  :thumbsup:

 

It is not exact like the correct tool but works good enough. (Or close enough for government)...  :lol:

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I was about to post adjusting the tab, then saw you already did it. I had the same problem after rebuilding a carb one time, and bending the tab fixed it.

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