Carb overflow

DAVE81CB750

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I've got slight drips from carbs 1 and 2 overflow. Happens when fuel on or off. I have replaced the bowl drain screws and still happening so I was thinking it's maybe a hole in float bowl or overflow tube . Any thoughts guys? Has this happened to any of you ?
 
Yes but the fuel that is left in the bowl after turning fuel off eventually drips out so was thinking it got to be a tiny hole in the bowl tube or just at the bottom of the tube ?
 
let the fun begin staggy i had the same problem and ended up taking them off for major surgery, but i did them when it was nice warm weather , they are a swine to get off and back on again when the rubbers are cold. just noticed you haven't got the air box? maybe a lot easier then
 
I also found the carbs a hell of a lot harderto remove if the boots are old. And if you're taking the carbs off, might as well change out the fuel rail tube o-rings.
 
I have drained all the float bowls and measured the fuel and they are all the same . So I was thinking that this wouldn't be a float valve problem? And maybe the float bowl. That's what is leading me this way before stripping carbs.
 
Look at the overflow tube. Sometimes they crack and fuel drains out of them that way.
Oh, I've seen fuel rails leak because the Orings go bad and the fuel runs down the carb body and drips from the bottom, appearing like it is coming from the bottom.
 
Oh yes thanks brett . I will have to inspect, great ! Bloody carbs !
Just buy new needles and seats from cb750 for a reasonable cost. You don’t need to take much apart. Pull the carb bank and just the bottoms off the carbs and leave them connected. I wouldn’t dismantle any more if it runs fine. An hours project so no big deal. Of course look for corrosion but 99% of the time this fixes them.
 
Just buy new needles and seats from cb750 for a reasonable cost. You don’t need to take much apart. Pull the carb bank and just the bottoms off the carbs and leave them connected. I wouldn’t dismantle any more if it runs fine. An hours project so no big deal. Of course look for corrosion but 99% of the time this fixes them.
I would add that bench testing the carbs is a good idea before reinstall. Put a fuel line on the primary inlet, continue to fill the fuel line until the fuel stops draining into the carbs. Wait for an overflow. If nothing, you're good.
 
I would add that bench testing the carbs is a good idea before reinstall. Put a fuel line on the primary inlet, continue to fill the fuel line until the fuel stops draining into the carbs. Wait for an overflow. If nothing, you're good.
Bench test never hurts. I just blow in the fuel inlet and if they seal when you push the floats up they are probably good.
 
Bench test never hurts. I just blow in the fuel inlet and if they seal when you push the floats up they are probably good.
I should note that needles and seats are available from Vintage CB750 for less than $8.00 each.
 

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I've got slight drips from carbs 1 and 2 overflow. Happens when fuel on or off. I have replaced the bowl drain screws and still happening so I was thinking it's maybe a hole in float bowl or overflow tube . Any thoughts guys? Has this happened to any of you ?
Rebuilt 81K Carbs no leaks off bike. But as soon as I crank to start. Gas pours from #2 (Main) Carb. Took off checked did off bike leak test.. Again once cranking t6o start. gas pours from #2 carb. Is there a a pump or suction while running? WB Houston,Tx
 
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