Topic: Carb problem, no fuel flow when bowl is installed

[stickman]

Morning gang:

1974 CB750 totally stock with original carb rack.
Carbs have been removed, cleaned, reinstalled.
I have replaced all fuel lines keeping the metal tee and cleaning it.
After reinstalling the carbs, removing the floats and float valve, I have
blown air thru the fuel lines and out thru the float valve seat, all is good.
Reinstalled floats and float valve, leaving bowls off, turn one fuel and strong fuel flow
on all 4 carbs.  Work the float up and down and float valve works good turning gas flow of and on with float movement on all 4.
Installed all 4 bowls, turned on gas to fill up bowls and 2, 3 and 4 are good.
Bowl number  1 no fuel flow period.
Replaced float, float pin, and float valve with known good one, no change.
tweeked the 2 float balls comprising the plastic float moving them inward delicately
in case the float was hangin on the bowl.  No change.

I am now officially out of ideas. 
There is always the possibility that the float needs to be tweeked further inward
increasing bowl wall clearance but I am guessing thats not it.

The float and float valve move freely and gas flow cuts off and on manually moving the
float up and down with the bowl removed.  When bowl is replaced, no fuel flows into the bowl.

Any thoughts or suggestions?

[flybox1]

swap floats with another bowl and see if the problem follows... if yes, its your float still contacting the side of the bowl.
could it be upside down?
if NO, swap bowl #1 with another bowl, and see if it follows....

[greenjeans]

probably the usual - the float is contacting the side of the bowl or the gasket restricting it's movement.
If your float needle and seat are working (as you stated) that's about all it could be.

[scottly]

Plugged up vent tube?

[dusterdude]

Your gaskets are hanging up on the side of the floats,ask me how i know.gj didnt read your post,what he said

[stickman]

I have further tweeked the float to move it further from the sides, no help.
I have clear fuel lines installed so I can see fuel flow.  When I push the bowl fully into place and just hold it there and turn on the fuel, no fuel flow into the empty bowl.  However,
if I ease off on the bowl and let it drop away from the gasket maybe a 1/16th of an inch,
full fuel flow.  So Scottly, you may be onto something with the plugged vent hoses.
Will check in the A.M. 

Thanks guys for the ideas.  Keep em coming.    Stickman

[mrrch]

Check the float towers for small burrs that catch the float arm (Hondaman talks about this in his book)