There really isn't a voltage limit on any electric motor. It's more of a how many total watts can it do before it fries kind of thing. The thing could run fine on 50 volts as long is it's never asked to pull more than a couple amps. Of course you could eventually get to the point that the rpms cause the rotor to explode too.

That being said, listen to the previous posters advice. That much motor with that much voltage is just asking for the smoke to escape. Not to mention drive-ability issues.