Hey all I've posted this issue once before but I did not give much info. Once the the bike warms up the RPMs will rise a little and then I hear a "PFFT" then the bike almost dies but recovers the RPMs. I finally saw a puff of smoke come out of the carb. Ok so I have a lean condition? BUT the bike runs good in all conditions and the plugs have a brownish tint on the electrode. What I've noticed lately is after a ride I'll leave the fuel valve open and after 10 minutes of sitting theres a puddle of fuel under the carb. I'm running an old sporty tank with no pressure relief. Just on the fuel cap. There are times when I could hear it hissing. Could this have an affect on the carb? I'm lost at this point. Please help. Thanks
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VM34 issue?
- Thread starter Tia813
- Start date
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- carburetors
The float valves on the carbs are not a complete shut off. The petcock is used to make a complete shut off of the fuel.
Sounds like the vent on your tank may be plugged. Every fuel tank must have a clear vent to let air into the tank as fuel goes out. If I remember correctly, the harley tanks used a vent line running form the gas cap area down to the bottom of the tank. I think it was jayel that talked about the harley type of vent.
Sounds like the vent on your tank may be plugged. Every fuel tank must have a clear vent to let air into the tank as fuel goes out. If I remember correctly, the harley tanks used a vent line running form the gas cap area down to the bottom of the tank. I think it was jayel that talked about the harley type of vent.
Thats what I figured. According to the Harley shop I bought the cap from he said that the vent is built into the cap. So if theres pressure that is not released from the tank could that affect fuel flow? I'll do a search on Jayel's post
Ironsled77
XS650 GRAND HACK
What's your float height? I had vm's on my last xs sucker leaked all the time. It was a bad needle n seat and a slightly off float.
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I thought the float height was not adjustable since the manual did not have any directions. Before I put it together I flipped it upside down and the tab was not level with the carb body. It was sitting high. I'm pulling the carbs off tonight so what part do I bend to adjust the float level?
I am Carbon
shade tree mechanic
Gineric instructions
Float level is adjusted by moving the tang that contacts the float needle. Floats must be
level (same reading on each side); this is done by adjusting the bridge between them.
Carbs must be adjusted to the same float level.
A procedure is to read float height. This is measured from the surface on the
carb body on which the gasket seats to the top of the float, with the gasket removed. If
the gasket cannot be removed without damage, reduce the specification given by 1 mm.
and measure from the gasket. Holding the carburetor with the floats up, lower the floats
gently onto the float needle, taking care not to compress the float needle spring. Since
the reading is taken with the carb upside down, raising the float level will lower fuel
level, and conversely.
Float level is adjusted by moving the tang that contacts the float needle. Floats must be
level (same reading on each side); this is done by adjusting the bridge between them.
Carbs must be adjusted to the same float level.
A procedure is to read float height. This is measured from the surface on the
carb body on which the gasket seats to the top of the float, with the gasket removed. If
the gasket cannot be removed without damage, reduce the specification given by 1 mm.
and measure from the gasket. Holding the carburetor with the floats up, lower the floats
gently onto the float needle, taking care not to compress the float needle spring. Since
the reading is taken with the carb upside down, raising the float level will lower fuel
level, and conversely.
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Tia813, I don't know what manual you have, but the Sudco Mikuni Tuning Manual has explicit instructions for adjusting float level in VM-series carbs. If you have the Sudco manual, take another look.
