Carburetor hoses

[schatenjager]

I have a dumb question. I took the carbs off my 77 GS750 to be rebuilt. The guy that rebuilt them did a great job and the bike is running once again but, when I took the carbs off I didn't remember to notice where the two hoses that are spaced between carbs 1/2 and 3/4 are supposed to go. Currently they are simply running down through the intake boots and not connected to anything (the hose that comes from the 2/3 position is of course connected to the fuel petcock for the diaphragm). Can anyone tell me what these two carb hoses are for and where they are supposed to go (if anywhere)? The bike starts without them connected to anything and seems to run fine.

[chiphead]

I think those are breather/overflow tubes. Run them down the back of the crankcase to the right of the rear tire.
Some models that I don't remember may have had them routed up and over the back of the airbox.

[Roland]

Hi schatenjager,

It sounds like you are describing the carburetor vent tubes. If so on my 79 GS750 they wrap up and over the air cleaner and hang just behind the air cleaner.

[mark]

Nice pics! Actually those breather tubes are on the #2 and the #4 carbs. Everybody else is right, they vent to air. #3 carb is the vacuum line to the petcock.

[psyguy]

my airbox has a bracket at the back (and to the right) so you can run both hoses through it

[schatenjager]

Excellent, Thanks! And those were fantastic pictures!

[tjhenry]

so i found those tubes tonight as well, what exactly do they vent? my bike is a 1977 GS750

im' having gas leak problem, and i'm replacing the petcock when the parts come in, are these tubes where the gas is coming out of mostly?

i've seen a little in the box with the air filter inside, and im' a little worried, i put in seafoam and ran the tank dry, and now i'm having either a petcock or float problem

[TheCafeKid]

so i found those tubes tonight as well, what exactly do they vent? my bike is a 1977 GS750

im' having gas leak problem, and i'm replacing the petcock when the parts come in, are these tubes where the gas is coming out of mostly?

i've seen a little in the box with the air filter inside, and im' a little worried, i put in seafoam and ran the tank dry, and now i'm having either a petcock or float problem

The vent tubes are mainly there to vent air from the bowls so they can fill. Usually gas WONT come out of them. Thats what the overflows coming off the bottom of the carbs are for. Check your float levels, make sure they are correct. 26mm +/- 1mm...

[tjhenry]

and i'll have to take the cabs off to do that correct, since they are on the inside?