FZRSupport: the FZROnline Archive

I just got a second set of carbs off ebay for my FZR 400. They look identical. Jetting is identical, but the new carbs have an extra hose connection. Any idea what it is?
What connects to it? My bike does not have this. Large Brass tube in Photo.

It looks like a vacuum take off, see if it comes out in the inlet manifold engine side or carb side of the butterfly. That will indicate if it's variable or not.

Thanks evil one!
It does have an opening in the carb throat, a very tiny one. But it is a vacuum of some kind. Apparently these are California carbs.