I think they are for venting the gas fumes but i may be wrong.

 

Two little black rubber hoses hanging down under the bike--I am assuming one or both of them are for venting crankcase gases like a PCV valve in a car?

Coolant tank overflow - is the one of them

 

The crankcase vent is routed to the airbox. No vehicle has crankcase vents to the open air any more.

Two hoses come from the carburetor overflow on first generation bikes. There is one line from the coolant overflow and one from the recess around the gas cap (to drain off rain water).

 

Water and gas if you manage to over fill... stand it up straight, on a warm day, fill to the brim with cold gas from an underground tank, let it sit in the sun... come back to a puddle of gas under your bike.