Did you reconnect the rear carb vacuum line to the petcock? Open a float bowl drain bolt and see if gas flows out. It might take some cranking to get the fuel into the bowls when starting dry.

 

I did connect the line to the petcock. I will try to find the drain bolt. I will let you know what I find with this.

 

Spray some carb cleaner or ether into the carbs and see if it will fire up. If so, definitely a fuel issue. If not, you probably have something up with the ignition, maybe a wire got disconnected?

You may also want to get somewhat longish piece of vacuum hose and attach to the bottom of the petcock. Apply some vacuum and see if fuel will flow out of the fuel line. It should also shut off when you release vacuum from the line.

 

Update: I sprayed some starter fluid into the carbs and it fired up for a second. So I checked the petcock and fuel pump. Both had the same gelatinous crap that my float bowls had. I cleaned that up and the bike will now start, but the slightest amount of gas will kill the engine again.

It looks like the rear carb may not be firing now. At least the throttle slide isnt moving.

 

...So I checked the petcock and fuel pump. Both had the same gelatinous crap that my float bowls had. I cleaned that up and the bike will now start, but the slightest amount of gas will kill the engine again.

The whole fuel system needs a thorough cleaning, tank, petcock, pump, carbs (again). Stalling when the throttle is cracked is a classic sign of clogged pilot jets. The jets must be removed to clean. Hold them up to the light, visually inspect to ensure they are clear.

 

I had the exact same problem with mine that sat for a decade. Took 3 thorough cleanings to get it right. Make sure to take the Jets out, soak them, poke them out with an ultra fine wire. Then, blow all the circuits in the carb bodies till they flow clean. Make sure you have the diaphragms out. Finally, blow all the little bleed holes in the venturi out, mine were all full of crud and that what I missed on the first 2 cleanings. If throttle kills it, I'm sure it's the pilot circuit.