I am wondering where the dyno came from, really. If the hobby store sinced moved (hence that is why you order parts), have you dynoed the motor lately? I've been a regular racer at only two hobby stores Fantasy World and Tacoma R/C Raceway ( which the owner is a sponsered Losi driver), so far and I didn't see anyone with a motor dyno, 'cause if they did, I would have been nagging them all the time!!!
Did you hobby store have it?
When was you motor dynoed? Before or after you start using your motor at high amps?
Keep in mind that running the motor, at any given speed, will wear down the comm. You will have to get the comm cut, clean and lube the bearings, clean the can, re-shim the armature, reset the timing, break in the brushes, and finally dyno the motor. Did the motor come packaged with a lable stateing that it put out 68,000 rpms? If so at how many amps?
an inquiring mind wants to know.......... 