l am building a custom bike with a 2000 sportster 883 engine.Off the carb, there is a T-connection where there are three hoses.One is connected to the carb, one goes to the tank, one is for tank overflow, then what is the other one for?Thanks.

idk

exhaust

Air Gas And Some other shit that makes big exsplosins!

What l can see based on the data is;
vacuum hose ,fuel bowl drain hose, fuel hose
an article used for something else explained the 3 hose's

Carbs will have at least 2 hoses, one for the fuel going in and another from the bowl in case the floats stick. The fuel will exit the hose instead of flowing into the engine.

A 3rd hose will probably be the float bowl vent. Some go to the air cleaner so the fumes can be burned.

Another hose could be a vacuum hose, sometimes used for emmissions control, ignition advance or to ''talk'' to the computer.