Carburetor tube question

[alehman]

Hey all,

sorry if this question seems silly, but what is this tube that comes out from the middle of the carburetor setup? If the tube on the left (in this photo, no tube is connected, but it would go on the brass tube) is the fuel line, what is the one in the middle. Very new to carb work and motorcycles in general.

For the record, I have a 1979 CB750 Limited edition.

[Re-run]

if it is the black tube there, My guess is that is a venting tube to equalize pressures between the 4 carbs.

[alehman]

pressure in what section of the carbs? and do you think it's something that should have a filter on it?

[Re-run]

Nope no filter. It just allows the air pressure inside the carbs to be equal.

[alehman]

Thanks!