Open the high-speed needle valve about 1/2 turn from wherever it is right now, and then work on starting the engine at 1/4 to 1/3 throttle. You should be able to get the engine to start and accelerate to full (keep the battery on the glow plug). You can then reset the engine.

Very likely, the idle mixture's too rich, which is causing the backfiring when you try to open the throttle. Get the engine started at a higher throttle setting and go from there and reset the engine. As the weather changes from day-to-day, you'll find that the carb settings will change a bit as well.