I forwarded you questions to Bob; here is his response:
The reason a non-sensored motor feels like it does is because it is what you call a slotless motor design and not a slotted sensored design like Novak and the other car racing motor manufacturers make.
Since a slotless motor has very little iron in it, the magnets do not have anything to cog against. This feature is what gives the motor its free wheeling characteristic which most car drivers do not like.
There are two ways to make a slotted motor feel this (smoother) way and both ways decrease the power output of the motor and overheat it. One is to run very weak magnets and the other way is to have a very large air gap (small diameter magnets). We could do either but nobody but a very few would want to run them.
It is not a good idea to grind the rotor down because it is a very difficult and messy operation. If you do want to try it you must apply a coating of epoxy over the magnet, after you finish, to prevent the magnets from rusting.
Im a great fan of Novak BL systems, I have 3 of them all XBRs
with EX motors. I havent switched to sintered yet but Ive tried
and always reverted back to the old bonded rotors because it
felt more free off power and revs smoothly. Recently, my brother
bought CC Sidewinder system, the motor came with a sintered
rotor, so I thought it'll be hard to turn or twist (the shaft) by fingers.
But was very surprised as it has almost no resistance at all.
Can you make a sintered rotor like this? Bought a Velocity Light
motor last 2009, Steve told me that it has torque and lesser
resistance but it's still hard to turn, went back to the old EX motors.
Im waiting for the Kinetic, I have a new chassis to work on this
year. Bonded rotors are phased out so Ill be stuck with Ballistic
motors. So can you make a sintered rotor that'll work smoothly,
with very less resistance like the ones in CC motors? Or can I just
modify the stock 12.3mm motor by grinding it to 12mm or less?
BTW, drag and street racing is my game so I really have no use
for natural drag brakes or any form of engine brakes.