Fisher Price Overheating Troubles

[DampRobot]

We have been using two Fisher Price motors on our shooter, using a combination of an AM planetary and sprockets to gear the motor down and then up again. The final ratio is about 1.8:1 (reduction).

We are using the 0673 Fisher Price motors (the ones with the wattage similar to a CIM), and have been having lots of problems with overheating. We are getting mediocre performance from the shooter (about 13 feet), and have already fried at least one motor. Overheating really the problem, in my mind. We are running a motor that has much less thermal mass than a CIM around the CIM's wattage. To me, its no wonder it is overheating.

Some more data: we were using an optical tachometer (the type used to measure the speed of a model airplane prop) and getting a speed spinning freely of about 4800 rpm. The motor is drawing about 37 amps accelerating and 27 steady state.

To me, these numbers show that our setup is very inefficiency, and we could significantly reduce our overheating issues by using a more efficient reduction. What is a good solution to our overheating/inefficiency problem?