New here with a question

[farmlife]

I just bought a 1977 CB750. I bought the bike from a guy that was going with a cafe look. Not what I'm going for. I'm planning to change this bike into a bobber chopper. I'm cutting the frame and going to weld on a rigid rear end. Hopefully I wont have to rake the neck but soon I will figure that out. The bike has 72 or 73 carbs on it.  The guy told me he bought the carbs rebuilt but he stored the bike for about 13 months. Before he stored the bike he drained all the gas out. I bought the bike without hearing it run but the price was to good even if the motor didnt run. Got back to house with it put some fuel in it with a little marvel oil. A couple kick starts and the motor fired up. I was very happy but the bike will not stay running. The problem I'm having is when fuel is going to the carbs after awhile the hoses coming from the bottom of the bowls fuel squirts out. Frist it started with #1 carb. I removed bowl and moved float up and down and put the bowl back on. Having same issue with #3. When the bike is cranked it is not wanted to stay cracked at idle. Thinking I just needed to run the bike I took off down driveway the bike wants to cut off when taking off in 1st. You have to have choke half open to get get going. I'm not a carb person in means but any advice would be great. What is the deal with the fuel spitting out the hoses? Thanks

[cbrydr]

the tubes in the bottom of carbs are overflow tubes --gas comes out when float needles do not stop flow when bowls are full---check the rubber tips on your float needles to make sure they are not cracked or half gone ---make sure every thing is clean and moves freely--put a fuel filter between tank and carbs---a grain of sand or a piece of rust will hold needles open enough to cause a problem   THESE BIKES ARE COLD NATURED---RIDE IT 4 TO 5 MILES USING THE CHOKE AS NEEDED THEN IT SHOULD BE WARMED UP ENOUGH TO TELL IF IT'S RUNNING RIGHT--

[Polymer-2]

When you had the float bowls off there were some little brass tubes sticking up from the bottom. These are bad about cracking. I don't know why.
Put a piece of rubber tubing on the end of the tube, submerge the float bowl in water, cover the drain with your finger then blow in the tube and see if there are bubbles coming from the side of the tube.. Do this to each float bowl that leaks.
If you find a crack then sand the tube it until it's clean then solder up the crack.

[Polymer-2]

cbrydr wrote

the tubes in the bottom of carbs are overflow tubes --gas comes out when float needles do not stop flow when bowls are full

Yes and they crack. Then fuel runs out all the time.