If the motor is running hot its genrally a sign of undergearing as the motor is revving too much, but sometimes it can be caused by excessive over-gearing causing too much current draw due to the large load. I dunno what to say really, if you can gear it down even further and see what that does for the temps maybe. All this is assuming there isnt any outside issue like binding in the drivetrain or what not- take a look at your esc settings and lower the timging and start power if possible...
