In my 3rd year of an '02 X-Star, I started feeling a vibration.
Turned out to be the grease in the rudder was mostly gone. So at high speed, the rudder was fluttering (rhymes, eh?).
I got a grease gun, pumped a 1/4 tube until it was filled back up. Vibration went away.
I was also told to make sure there is no vertical play in the rudder shaft. If so, adjust the nut a turn or too. Not too much of course, or you won't be able to steer.
(Message edited by awf_axis on May 30, 2006)