I have alot of vibration in the throttle side only of my 2000 fatboy. i have drag bars and have changed the grips to accutronix grips with rubber inserts. hand goes numb after awhile and around 65 70 mph ant help.

 

I had similar problems and got a cramp buster. Also wear padded gloves.

http://www.crampbuster.com/

 

Check your riser bolts and make sure they are tight too.

Drew