I have a weird issue. I just instaled a set of T-bar drag bars. The following day I rode the bike to work 20 miles, no problems. On the way home I noticed this vibration in the bike. The weird thing is, I can feel it all over, more so in the seat than in the bars. It doesn't do it when I am sitting still, I need to be moving but it doesn't matter what gear and it doesn't seem to be engine speed dependant, more bike speed dependant, and it doesn't do it all the time. My tires have maybe 150 miles on them and I checked and the wheels weights are still there. I have read that some people will change to the urathane bushings are going to drag bars as the stockers won't hold up. Is this possible I would feel that in the seat or is it more likely I have a drive line issue? I had just changed all the fluids about 100 miles ago and the primary chain seemed fine so I didn't adjust it. The bike just hit 15,000 miles. I did have it up on the lift today and spinning the front wheel is fine, no noises or play anywhere. Spinning the rear I can hear some noise from the rear of the primary area but not sure if it has always been that way or if this is new. Any input would be great.

 

One of the possibilities is that one of your attach points for the exhaust pipes is loose, letting the pipes touch the frame.
Tom

 

I'd also check your final drive belt. Mine was looser than normal and was giving me **** in 5th and 6th gear. I could feel that it was starting to get no bueno in the other gears though. Might be your issue.

 

Do you have (or had) stick-on wheel weights. Sometimes these things come off tape and all. It may be real hard to know if you have thrown one. I've throw a couple of weights off the rear wheel of my FXSTC. If its all bike dependent vibration and not RPM related then I would look to the tires before I went to anything else.