Cb750 carb pouring fuel

Hey guys I wanted to see if you all might be able to lend me your expertise. I have a 73 cb750. The bike has been running and in good working order for awhile now. When I first got the bike i went through most of the recommended maintenance stuff and the carbs were an issue. I had to re-jet/clean them and its been running great ever since. Anyways i went to take the bike out yesterday and after right after i started it I noticed fuel pouring out of the #2 carbs nipple. After turning the fuel off it eventually stops pouring out. Im guessing the float may be sticking? However I wanted to get some thoughts from you guys before i dig into them. Pulling the carbs off the first time was a huge pain in the ass and i never replaced the boots so needless to say Im not looking forward to this. If you guys can give me an idea of what to look for or if there is simple way to tackle this task any help would be greatly appreciate.

Thanks in advance!
tony

How old are your rubber gaskets? I had to pull my carbs off and put new ones on. No more leaks.

Well this is leaking out of nipple so the gaskets wouldn't cause that would it? However its been a long time since I had them apart so I may be mistaken.

Likely a piece of dirt stuck in the float valve. If you can take the bowl of that carb off without removing the carbs, then do that. Put something under the carb and turn the gas on for a couple seconds. That should flush out whatever is keeping the float needle valve from seating. If that doesn't work, you will need to remove the carbs and clean them.

Your #2 float could also have a hole in it, causing it to sink and not close when the bowl is full.

I have had a pinhole in the float, as flug said above, check for that. Pull the float and shake it to see if there is fuel inside. Better yet, drop it into some fuel and hold it under the surface for a bit to see if you have bubbles. Not sure if you have copper or plastic floats, but this problem would be more likely on copper floats.

I have also had bad gasket kits that interfere with the movement of the float and cause it to stay in a lowered position and therefore not shut fuel off. Check that as well, especially if your carbs use the "paper" type gaskets. Remove the carbs and leave the gasket on and ensure that there is no resistance whatsoever. There should be at least 3/16" clearance around all sides of the float from the gasket.

I've ALSO had multiple cracks form in the brass overflow tube that caused fuel to pour out even though the float was working properly. Place the bowl level on top of a cup or container and fill it with fuel right to the top. Come back in 20 minutes. If the fuel is lower than where you left it, that's your problem.

Put a drain tube on each nipple for one so gas goes on the ground not the motor, but try just wrapping on it with a wood hammer handle, open the petcock and see if it stopped

Wow guys, thank you all for your help and suggestions!I'll get on this and report back my findings.


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So before I even pulled the bowl I took the advice Tune-a-fish gave me. I gave it a couple light wacks with a mallet and it must have freed up the whichever part was sticking. Now I'll just have to see if happens again. Although I imagine this may be a sign that I will need to clean the carbs again soon.
I never let it sit for very long with out running it, but it has def sat longer than it ever has since I first cleaned the carbs.


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Either that or gasket interference. I had the same thing happen when i was having gasket issues. A couple taps with a screwdriver and it 'clicked' into position. Just be wary as it could get stuck later down the road if this is the case. Next time you pull the carbs definitely inspect the float to gasket clearance.