I have had a few new JKRH with this same problem. I break all my motors in the same. "Dry break in until the comm is dirty all the way across, sometimes taking 15-20 hours on 4 volts."
I am having what seems like "turbo lag." The motor seems to not have any low end power and then all of a sudden it takes off. Then slow down to go around a turn and it has no power again. Half way down the straight it takes off. I know I'm not the only one to have this problem. I also noticed it this weekend in the Orlando area. His motor was good after the race was over.
So my question is how many of you have had this happen to you?
Do you just keep running the motor or throw it away?