Yep, it sounds like a fuel delivery problem - especially since you said it came with the gas tank empty.
Use a clean glass jar. Turn off the petcock. Remove the rubber fuel line from the carb. Turn on one flipper of the petcock, and allow fuel to flow into the jar for maybe 10 or 15 seconds (not just 1 second), then turn off the petcock. Look at the fuel in the jar - any dirt/particles in it? If clean, pour it back in the tank. Repeat with the other flipper of the petcock.
Sometimes one side of the petcock works, and the other side does not. The "reserve" side often gets clogged since it seldom gets used. I usually turn on both sides for short around the block type trips - just to keep the reserve side exercised.
If you do NOT get a good flow of fuel out of the hose, either the filter in the tank (it's on top of the petcock) is clogged, or the petcock itself is clogged. The flipper-type petcocks are prone to clogging, especially as the years keep going by. The reproduction ones are even worse! If your problem is up here - shout.
In the carburator, there are two common places where a fleck of dirt or rust can gum up the works - the float valve, and the main jet. Let's hit the main jet first. Carefully turn the main jet needle clockwise - counting the turns - until it seats lightly. As Mutt said, it's about 1-1/8 turns. Take a piece of shiny paper junk mail, and crease it long-wise. Have a helper use this "ramp" to direct fuel from under the main jet needle to your clean glass jar. Turn the main jet needle counter-clockwise until it comes out. Now turn on the petcock. You should get a good flow of fuel out of the hole. Any dirt in the jar?
Turn off the petcock, screw the main jet needle back in until it seats lightly, then back it out the number of turns you counted before (about 1-1/8). Sometimes this dislodges a tiny piece of dirt or rust, and it will start and run now. Over the years, I've had this solve the problem many times.
If not, it's time to look at the float valve and float setting. Remove the rubber fuel line from the carb. Remove the three screws holding the top of the float chamber on. Carefully (don't damage the gasket!) remove the top. The float bowl should be about half full of clean gasoline. Clean it out if not clean. Flip the top of the float upside down. Remove the little pin which holds the float in place, and carefully remove the float. Give it a shake - it should be nice and light - full of nothing - but sometimes (not very often) the float will develop a pinhole leak. Turn the float cover upside down, and remove the float needle. Any dirt where the needle is? Blow into where the fuel line goes - to make sure there's no dirt stuck in there.
The last thing is to check the float level. Here's what it should be.
- float.jpg (44.08 KiB) Viewed 12989 times
OK, as you've started to disassemble your carburator, you've realized:
YOU NEED A SERVICE MANUAL. One place to get one is your local Harley dealer. Have him order Part# 99444-93 called 1958-1966 American-Made Lightweight Parts, Service, Color and Accessories. $40 He should be able to get it within a few days. Some folks listed in the Parts section of this website may offer reprints.