your using a brushed motor with a decent LiPo battery, 5000mAH = 5 Amp Capacity, with a discharge of 40C your able to push (discharge X Capacity) 200 amps. your ESC is rated at 35A (you might be fine here as your motor can't draw that much right now) but your definitely pushing a lot of power to your motor and brushed motors are notorious for getting hot, i would consider ditching the brushed motor if you want to run the LiPo battery and go with an entry level brushless.
conveniently you can just look no further then the Granite BLS for a good motor to slot in: http://www.Arrma-rc.com/part/AR390095
if you decide you want to upgrade the ESC http://www.Arrma-rc.com/part/AR390096
that's the ESC for the BLS.
the down side of the mega really is that it's not meant to run lipos the info on the Arrma website even state that the ESC is only meant to run with NiMh batteries. Long story short is you've got too much power for the electronics of the Mega and your going to continue burning up motors and eventually the ESC until you upgrade them.
i thought about it, but like i said. i got a kraton in order, so really no point of getting upgrades. have "2 year warranty" till i get that good set.Hi
The reason you guys are burning up your motors is because they are stock unmodifiable motors, even the Traxxas Titan motor are stock unmodifiable motor. Has anyone ever thought about upgrading to a good modified motor. Most modified motors have bearings, removable brushes, timing advance, and you can take them completely apart to do a good cleaning.