Unless it has been modified they could be vacuun supply for the auto petcock and the evap system valves for purging to the cannister. But I have an old bike with none of that so may not be the best help.
Check this view.
I'll check it could be a return, though I'm not sure why it would go through the intake manifold. There is another line coming straight from that radiator to the carb that I would assume would be the feed.