Fastest BL motor on 6 or 7 cells?

[captain harlock]

Well, as I said befor, the Lehners are the best and you can consider buying the Basic 4200, too. With 7-8 cells, the 40s are within your grasp. And once again, use the appropriate GR.

Check your drive train and the bearing as well, for they can over work the motor if there is something wrong with them.