Originally Posted by benben10

i would guess max rpm on a standard 7.2v pack would be about 20-25k. you will not find a kv rating on it. that is a cheap brushed motor and max rpm can very even between runs because of the condition of the commutator and brushes.

i would suggest finding max rpm by experiment. either with a baseball radar gun and calculating rpm from speed, or with some kind of tachometer (data logger or telemetry system), or even an RC airplane/heli blade tachometer and put a small propeller or stick of wood on the end of the motor shaft.

it might be more helpful if you ask for help with your primary goal. it sounds like you are trying use this calculator program to figure something out.