So often times I've seen small motors lock up because to little clearance on ring gaps. Especially air cooled ones, your better off being a little loose, still in tolerance of course, than you are being as tight as you can possibly get it. I say that mostly because it gives some margin for error if the motor was to overheat. Which is more of a problem with small motors that turn 8-16k rims, than it is our old iron. Lol when I build my motors I spec between hot street and endurance racing tables becuase of my right foot tendencies.