Is overvolting rc motor from 15v to 24v okay???

Is it okay if I overvolt a Turnigy Aerodrive SK3 (a 750 watt motor) rated for 15 volts by giving it 24 volts??? I also want to mention that it is specified that it needs 50 amps, but I can't give it more than 31.25 amps.

You could probably give that motor triple digit voltage, the practical limit would be the bearings and balance I guess as it may not be able to physically spin that fast. The voltage determines the top speed of the motor.

The amperage rating doesn't mean the motor NEEDS 50 amps, it means the opposite which is that the manufacturer thinks that's the maximum you should be putting through and still achieve full reliability. Note the current rating can be continuous or burst which are self explanatory (you'd think anyway).

The motor will only draw as much current as the controller supplies.

Until it burns up.

Heat is the killer. As long as the motor is not being overheated, you should be OK. You crank up the voltage, your going to want to drop the amperage, which should work for you as you cannot provide more then 30 amps into a 50 amp motor.

Now the motor is going to spin faster, KV = RPM per volt.