An easier way to figure this out. Your just doubling the voltage. So you need to double the resistance of the circuit. Measure the resistance of the motor with an ohm meter. Thats how much resistance you need to ad to go from 6 volts to 12 volts. Mine was 2 ohm. The wattage of the resistor is very important. That motor uses around one hundred watts. So you will need a resistor that big and it will still get very hot. My frist try the resistor got so hot the solder melted. So be careful where you mount it.


if it dosen't need fixed, break it