First, do you have a wattmeter? If you are going to play around with set-ups, you need a wattmeter to see the effect of your changes and to insure you are not over drawing on your battery, your ESC or overloading your motor.

Props are cheap. If you are going to experiment with your own set-ups, you have to expect to spend a few dollars on things to test. So buy a couple of props.

You have a 12X6 - What wattage does it draw, full throttle, on the bench? How does that compare to the motor's rating, the ESC's rating and the battery's rating?

Try it with another prop and see what happens.

Depending on what kind of flying you are trying to do you will need a watt/pound target to tune to. But if you are getting at least 50 watts/pound, And at least 4000 RPMs, it should fly, so give it a try. then try other props.

50 watts/pound - Caual flying

75 watts/pound - sport aerobatics

100 watts/pound - Agressive aerobatics - sport pattern

150+ = Competition pattern, 3D

So, what is your weight and what is your target?

Sizing Electric Power Systems -
Starts at post 2
http://www.rcuniverse.com/forum/m_43...tm.htm#4310056