I've known people to fill their handlebars with lead shot. #8 was the consensus, but hell, I don't know if it makes a difference.

Don't use steel shot, it doesn't have the same dampening effect apparently.

Also check the bolts and rubber in your risers. It makes a difference to have good rubber and properly tightened (not over tightened) bolts.

Not a real problem for me, but maybe my info will help you out.

 

i have the 01 sport too and in stock form the mirrors can get buzzy. i attribute this to short bars and long stems.
i did not like the feel of the bars so i put a set of 1974 hd bucks. i also cut the mirror stems and shortened then to my liking and welded them back together. as far as normal ridding (what's that) mirrors are fine but pushing it to the limit, they will rotate, so on occasions, i have to tighten the two screws in the rear.