Ray,

Crashcrash/Vic has a good question, is it a stock brushed motor or a brushless motor. Quickly, if it's a stock brushed motor, dump it and get a brushless motor and ESC...

A good tool would be an infra-red temperature gauge to monitor, motor temp., ESC temp and all electronic components. If done on a regular bases, it can give you a heads up on potential problems.

To start off, you started out at 90 degrees ambient temperature, so that's where the battery starts off at.

There's an endless list of what can cause a battery to overheat. Binding in any of the mechanical systems. Make sure EVERYTHING, moves smoothly. A bad servo can cause a battery to overheat, a bad BEC or ESC, a motor going on the down side. Yikes!
Even a battery that's going bad. If it's over a 130 degrees, you've got something causing the problem.

Heat related problems are one of the hardess to fine. Along with glitching.

If you have anymore details, please post.

Dave / Choppersrule