For low end needle adjustment this is what I use:
Warm up the engine and bring it to 1/3 throttle or just a little above idle.. Pinch the fuel line and hold. If the engine rpm's increase, it's too rich. If the engine quits right away, it's too lean. If it does nothing, it's really close. Now you need to tune it in the air... Run 'er up into the sky and idle it around a bit. Now gag it! If she quits, you'll need to richen it up and if it gurgles, lean it out.... Just make sure you're high enough to land 'er safely if she dead sticks.