In my custom micro monster truck the battery pack gets hot after I run it. I'm using a 1000mah micro battery pack and a epic binary 2 10 turn motor. The motor doesn't get hot at all but the battery pack get really hot. Hot enough that it melts the heat shrink wrap a bit every time. I just cut a hole in the rear window of the truck body to let some heat out. What else should I do to keep it from getting do hot.
You're running WAY too hot of a motor for those cells. They're not made to run anything near that. You need to either put regular, sub c cells in the car or go to a motor more fitted to the size of the cells. You can go with a speed 300 or something like that. But a 10 turn will cook those cells. I'm sure a stock motor would probably cook those cells.
If you're not racing this thing competitively, just go to a hobby shop and pick up some loose cells. They can be anything really. Sanyo 2400's, 3000's, or GP3300's. You can get unmatched cells very cheap. Especially 2400's.