fuel leaking through carburetor

[Joost D]

When the engine is running or when the petcock is on prime, the gasoline drips from the back of the carb. It seems to be coming from the 2 jets.
All rubbers and gaskets have already been replaced.
Does anyone have experience with this?

In the link is a gif where it can be seen clearly
https://media.giphy.com/media/tV8B3MBYL52t4hpMCM/giphy.gif

 

[JPaganel]

Either the needle valves are not sealing, or the fuel level is too high.

 

[Joost D]

after a full rebuild, the carbs continue to leak fuel at the rear through the jets, does anyone have an idea how to fix this.
The floats are not broken. When I test the float needle by moving them up they seal very well. When the floats are set to close the float chamber with the least amount of fuel, the problem remains and the fuel just flows through.
I hope someone has experience with this and can advise me.

There is a video on Youtube where it is clearly visible:

 

[Hasty]

Hey JoostD did you ever find a solution for this? I'm having a similar problem and can't get it figured out

 

[tstidham]

That is a pretty good leak. Mine only dribbled a little out of the slide needle when my needle/seats were bad. Are you sure your floats actually float? If they are the brass floats they can get pin holes. Give them a shake next to your ear and see if you hear any fluid in them. You can also put them in a glass of warm/hot water and submerge them for several minutes. Look to see if you see any tiny air bubbles escaping. Another test is with only the fuel bowl off, invert the carb upside down so the weight of the floats closes the needles and blow into the fuel line. It should take some force to overcome the floats and blow through them. It can also be a bad seat body to carburetor body seal. This guy shows what I mean using a small hand pump, but any air pressure can show these same results. How to test the float needle and seat for good seal! THE MOST OVERLOOKED PART IN CARBURETOR! - YouTube

If they are all sealed up right, then make sure to set the float height. Those fuel inlet setup look different from my 1978 model, mine has just a connecting pipe between the carb and the fuel inlet passes through the left carb to fill the right one, but if they are the bs34's, I'd set the float height to 26mm and see what you get.