How hot is your motor getting? Normally if the mesh is not right the gears will strip or melt far before the motor gets to hot. So I am sure it's not your mesh that is causing the excess heat. Your gearing could be the reason, or particular running conditions (high traction low ventilation). So as long as you have followed the above advice, then I am sure your mesh is just fine. Maybe go to a lower gearing, or maybe your battery is to much for the motor (if your running a 3S or 4S lipo). If you put larger wheels on, then that would be the same effect as a higher gear ratio. As long as your motor is below 200C then you should be fine.