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Discussion Starter #1
Ok,

Wanna go sledding tommorow but we have a AC carb issue we can't figure out:

Machine:
98 Powder Special, 38mm mikuni carbs

One of the carbs will not shut off the fuel when the float is full.  If you remove the carb and hook up a hose to it and turn it upside-down the weight of the floats shuts off the valve well enough that I can't blow air though it, but when I install it and turn the fuel on, the floats fill with fuel, but they don't shut off the valve and fuel starts leaking though the jets until you turn the fuel off again.

I think the floats are getting jamed but we tried swapping the float bowls on the carbs and the same carb continues to leak fuel.  Nothing looks funny, nothing is bent, the tang looks fine, just can't figure it out.

If anyone has a suggestion I would love to hear it because we just can't figure it out...

Thanks,

schu
 

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hole in float, try to float it in a container full of gasoline.
Float adjustment wrong, make sure they are set to specs.
Also if the needle (needle and seat) or seat has the smallest amount of debris, or if they are worn at all, fuel will still get in. You may NOT be able to see this wear with your eyes.
Replacing them may be your best choice. But definitely check the floats by floating them.
 

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FIRST you need to check the pop off presure of the needle and seat use a pressure pump turn the carb upside down and connect the pump to the fuel inlet and pump it up to 5 to 7 psi pressure not vaccume and it should hold 5 psi indefinatly if not pull the bowl off and replace the needle and seat if this still don't take care of it check for small cracks in the carb body were the fuel inlet passages are you said you already switched floats and it still does it so the next step is needle and seat .
 Good luck
....SNORAT....
 

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May be a piece of debris getting in the needle/seat area, but when you turn the carb upside down the debris falls away from the seat area so the needle can shut-off.  Remove the needle and flush some gas through the carb.
 

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sounds to me like you were just told in the previous post about debris in the needle,im sorry i didnt read your first post completely right ...sorry,but its deffinately either a float or needle problem.
 

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odoa4, this happened to me earlier this year with 38mm round slides. Knew it was up for rebuild(carbs) so I bought 2 kits and did normal rebuilds on carbs(gaskets, float jets) and threw them
back on sled. Result. One of the carbs overflowed from overflow tub. Reason: Bad float seat(manufacture defect) Solution: used one of the old seat and valves
It cured my problem. Just a thought. Paul
 
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