Originally Posted by InspGadgt

Did you change the gearing? Too big of a gear on the motor (pinion gear) will make it overheat. Is the mesh between the pinion gear and the big plastic gear (spur gear) really tight? There should be a slight amount of play in the gears. Tight gears will cause the motor to overheat. What battery pack are your running? Too high voltage of a battery pack can cause overheating.

Here is a link to your car: http://www.hpiracing.com/kitinfo/106159/
You can download the manual there in PDF format. If after checking what I mentioned above you might want to contact HPI directly.