Gs550 1982 carbs aren't delivering fuel?? Why??

Like wow, Dude. It's gravity flow, and not complicated. Does gravity work where you live? Many bikes have a finger strainer inside the tank which you should have removed and cleaned when you removed the petcocks. Didja? If the bike's been sitting the tank may be rusted all to hell, and have already clogged up the carb's teensy tiny little, like, really small, orifices. If rusted, the tank needs to be pulled, cleaned and coated. There's some stuff called Kreem that mc shops have, and some other stuff I can never remember the name of. Google fuel tank sealant, dude, to, like, find fuel tank sealant. Follow the directions. When you're done and everything is spiffy, install some good aftermarket mc fuel filters to, like, filter the fuel, dude.

Replace fuel filter. Loosen the drain screw on the float bowl one by one. If the bike has a separate fuel valve and vacuum operated petcock, set up appropriately and start bike. Check flow on drain hose. If the petcock is just a simple on and off fuel valve, set to on and observe flow from hose. Troubleshoot from result.

Best thing is to check the float levels and the needle valves.

seems like you may have a leak with-in the fuel line / air vacuum pipe no suction. or a clogged in-line filter element.