If the popping sound is a backfire, it could be too rich. Your accelerator pump might be leaking into the carb throat. Float level might be too high, valve and seat might be stuck open, etc.
What's the story on the carb? Rebuilt? After shutting down hot, look down the throat of the carb and see if fuel is dribbling or pooling on the intake runner.
Ignore the ball and set the timing by lining up #1 wire with the rotor when #1 cyl is at TDC. You can put a straw in the plug hole or put your thumb over the hole or take off the valve cover and observe to determine when #1cyl is at TDC.
The BB will either line up or it won't but you'll at least know that your timing is set correctly.
