Motorcycle Questions? Ask a Mechanic.
Is that a fuel pump it is connected to?
Sounds like "out" would go to the carb.
The main thing is to get the fuel going into the carb float bowl.
Even if you have to modify a few things just get fuel to the carb and that will be a start. Once the carb bowl has fuel then it might run or it might need some tuning or other checks done.
Fuel must flow easily from the tank to the carb or if it has a fuel pump then that would pump the fuel.
If you had some pictures you could upload that would really help.