Have you done any mods. to the mm esc? With 4s, you should add a cap to help w/cooling...like this one...
http://www.rc-monster.com/proddetail.php?prod=35vcap
Use the one w/the leads...it's easier. Also, that motor may not last very long...not the best quality. When it blows up, look at the Medusa line or Neu line of motors. The cheaper motors just don't last very long....just a suggestion.
By the way,
WELCOME TO THE FORUMS!
1. MBX-6 T8 1900KV, RX8 ON 4S
2. MBX-5T 1520, MMM ON 5S
3. MBX-5 ONROAD CONVERSION 1515, MMM ON 5S
4. MRX-3 ON ROAD CONVERSION 1512, MMM ON 6S
5. TEN T 2650 T8, MMP ON 3S