Need help with vaccum line on 86 vf500!!!

here's a picture of the item i need some help with. the inlet for the small hose what does it go to? or is it let open? the hose on there is just some i had laying around when i was bored. This is an 86 vf500 with California emissions and the diagram on the side panel is not help at all. Also this is the piece that's attached to the underside of the carb plate.

Thanks!

Shawn

 

Can anybody help?

 

Not sure I understand...is it for the fuel petcock?

 

The diagram in my FSM shows that round valve to be an air vent control valve. The diagram shows the hose coming off the center of the valve (if that is the one you are talking about) vented to atmosphere.