I recommend that if you get into overvolting a motor that you buy a product like the cycle analyst, It will provide you with details like how many amps you motor is drawing, and it can even be used to govern the maximum amps allowed from the controller to the motor.

I overvolted a 24V curried motor to 40volts, and drove it for close to a year without any problem. then, on one fateful day, I cooked the motor by driving into a lot of gusty wind for over an hour.

A stalled motor ( or a motor that is loaded ) draws more current, it I had the cycle analyst, I could have set the maximum amps to 15amps or 20amps, and I'll bet that I'd still be driving with that same motor.