Use bearing blue on one side of each mating surface, assemble, nip up, disassemble then check for point of contact, something may be bottoming out and not allowing full tension to be applied, the after market rotors are not as thick as genuine and may require a spacer, the contact points should be on the oil seal spacer to spline boss on rotor to spline boss on pulley to nut, not the outside of the pulley to rotor. Hope this helps, I'm dealing with a collapsed lifter bearing on my old shovel.
in the aftermarket world they have a rotor with a wider spline for the bigger engine's as this is the normal , is this & EVO style thin rotor , was she tight enough down there if you know what i mean, + is the front pulley a good fit on the spline if thats worn it could be the cause as it move's about , no cush drive on a pri belt system or in the back wheel have too do it up tight
