What is the hose connection up under the tank for?

[fivestring]

CB750K8, it came without airbox. When I turned the gas tank over I found the petcock fuel line nipple was broken off. I found a $20 replacement at CB750.com.

But there is another hose connection up under the center of the tank, I am assuming it is a vent and went to the stock airbox but I want to be sure. And since I have no airbox, what should I do? Run a short hose off it with a breather? Block it off? Or just let it open?

There is also the hose connection coming off the valve cover I need to address. Any suggestions on what to do with that one as well? Maybe I should just route the crankcase gasses back up to the tank?

 

[cyclebuster]

there is a large hose off the valve cover that went to the atmosphere behind the engine. in 77 i think they added an evaporative canister on it, but you can just run it open behind the engine. the hose from the tank can just be run behind the engine, i have a couple that are just clipped off around the breather area.

 

[750Ksabin]

If your tank has a flip open lid over the gas cap then the hose conection under the tank in the middle is a drain for spillage whe gas is put in. It needs a hose going from there to behind the engine and draining to the ground.