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Carburetors , Where does this hose go? & Runs Rough

1slowCB

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edmonton, canada
I bought this 1980 CB750 a week ago and it hadn't run in 5 years. This is my first time owning a bike so I am not too knowledgeable about them. I decided to remove the carburetors and cleaned them up and the jets. I put everything back together but can't seem to figure out where this hose (black rubber hose) goes. The clear one is hooked up to the gas tank.
Can anyone guide me in the right direction?

Also, when I got it to start up, it ran really rough and couldn't hold idle. When it finally did, it would bog and die under throttle. Im guessing the carbs need to be synced. When the bike is running, it also leaks fuel out of the bottom (overflow, I believe).

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Check overflow tubes for racks. Remove each float bowl, fill each with isopropyl alcohol, and check to see if there is any leakage. If there is, empty and check very close for cracks along the length of the tube. Cracks can sometimes be repaired with plumber's solder and flux and a very powerful (I use butane powered) iron. Or you can try JB Weld but some say it won't last. If you didn't see a leak from the offending bowl, it is overflowing from a leaking or mis-adjusted float valve. Sometimes you must lap the seat with jeweler's rouge on a cotton tipped applicator, sometimes it is because the wrong or a hardened or cracked valve is used.

You really should seek out and download SeanG's carb manual.
 
Check overflow tubes for racks. Remove each float bowl, fill each with isopropyl alcohol, and check to see if there is any leakage. If there is, empty and check very close for cracks along the length of the tube. Cracks can sometimes be repaired with plumber's solder and flux and a very powerful (I use butane powered) iron. Or you can try JB Weld but some say it won't last. If you didn't see a leak from the offending bowl, it is overflowing from a leaking or mis-adjusted float valve. Sometimes you must lap the seat with jeweler's rouge on a cotton tipped applicator, sometimes it is because the wrong or a hardened or cracked valve is used.

You really should seek out and download SeanG's carb manual.

Thank you very much! I will inspect those parts and the manual seems very handy. Will definitely read through it.
 
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