don't feel bad guys my 6 cell setup burns up my motors all the time... i have to keep on soldering the wires back...this is the conclusion i came after burning like 5 motors...
the motors get really hot with the extra voltage...either ventalate your motors (ventalated bb cans work good) get a better heatsink or just run your car for a few minutes at a time with breaks in between...
also for those who wind there own motors get yourself some silver solder...it doesn't burn up as quickly as the other types of solders do and it can take the vibrations...
www.minizworkshop.com has some good cheap motors too