Hose routing for California emissions/3 line fuel tanks
See also: Carburetor photos
For California bikes with intact emissions-control systems
The color-coded hoses on the right and left of the tank go to the emissions system as shown. There is one gas line (purple) and one vacuum line (orange) from the petcock to the carbs.
The center port on the tank and the hose on the "T" fitting between the carbs are vents. They just run to the atmosphere. There is a small metal loop on the right hand side of the frame, a few inches from the bottom at the back of the motor. Run them through there and point them down.
49 state models have only one hose coming from the rear of the fuel tank. This is a drain hose for fluid that gets in the depression between the filler neck and the top of the tank, from being in the rain or overfilling the tank. Air vents into these tanks through the gas cap.
California models have three hoses: the drain hose plus two more. Rather than venting the tank directly to the atmosphere, the gas fumes are contained in a closed system.
In case you took all the hoses off your bike and can't figure out how to get them back on, here's how it's supposed to look when everything is in the right place. You may also want to consult the parts diagram.
For California tanks without emissions-control systems
Some people remove the evaporative emissions systems from their bikes, or install a replacement California tank on a 49 state bike. If you have a 3 line tank (California) but don't have the emissions devices, this is what you need to do:
Vent tube routing: 49-state bikes