The propellers on a quadcopter have two rotational profiles, counterclockwise and clockwise. Getting these right is important for proper flight. Take note, or use the picture below, to find out which way the leading edge of the propeller should turn. The kit comes with two sets of propellers.
Use a small plier to use as a lever to push the propeller off the motor shaft
Separate the new propellers into two batches, with the letters facing up; counter-clockwise (marked B1 or B2) and clockwise (marked A1 or A2) type
Use the picture above to install the propellers on the motor shafts. An easy way to remember the rotation is that the leading-edge/tip of the two front propellers always face each other and likewise on the tip of the two rear propellers.
If you have a damaged motor or a bent shaft, you can replace it with one of the two extras supplied in the kit.
There are two brushed motor types, counterclockwise and clockwise rotation. Motor rotation and correct polarity is indicated by the wire color:
Counterclockwise motor: white (+), black (-), grey back plate - for motor 3 and motor 2
Clockwise motor: red (+), blue (-), white black plate - for motor 1 and motor 4
Note: running the motors in their wrong direction will dampen its performance and lifespan.
Remove the propeller from the shaft
Unsolder the two wires from the main controller board. Take note of which wire goes to each pad, as this dictates the direction of rotation. The numbers refers to the motor in BetaFlight.
Untangle the wires from the arm and use a small screwdriver and push the motor out of its socket.
Replace the motor and solder the wires in place and put on the propeller as shown in the following picture.