I used a file and took some of the chrome buildup out of the knurled area. reinstalled with the proper torque and no problems since. goin on 6k since.

 

+1
I also got aftermarket pushings .. poly... something rock solid ..

 

check and make sure there is a gap between the clamp top and the risers when the bolts are tightened. if not then you need to file a small amount off the ends of the top clamp where they meet the risers so you can pinch the bars tighter without the top bottoming out before the bars are secure. hope this helps. and of course the bars do need to be knurled or dimpled so it isn't smooth metal against smooth metal.

 

bars too small, risier ID too big, no knurling on bars or risers.. just shim, file, or grind away whatever it takes to get the mothers tight..without messing up the finish...

 

An old timer trick that's always worked for me is to get a couple of external star(Lock) washers and put them in between the bar and riser (top and botttom depending on size).