...probably not a good idea; just using washers would still have metal to metal contact between the bolt and mount. I'm assuming your counterbalance system is operating correctly? While a certain amount of vibration is normal, there are ways and means of reducing it:
- 685 kit ( the lighter piston better matches the counterbalance weights)
- rubber pegs - some aftermarket pegs have removable rubber inserts for road use
- vibration dampening bar mounts (RoxRiser)
- vibration damped bars (sorry, can't remember the brand)
- thick grips (progrip 714's) or even foam grip puppies (not a fan, they don't hold up for the kind of riding I do)
I've found that a good set of bars and handguards helps (I use Renthals and Acerbis or Fastway handguards). I avoid all solutions that add weight/inertia to the bars like bar end weights, bar snakes, filling the bars with lead shot, etc. etc. ....these things can help with vibration but have other negative effects as well.
Hope this helps,