Just in case this happens to anyone else, 1st thing to check out:
I ride a 93 XLH883 & had a crazy vibration all of a sudden on my way home the other day. As it turned out it was the corner of my battery box that came in contact with rear rocker box cover. Just bent the edge of the battery box cover down & put it back together. Voila!!! Vibration gone..

 

Are you sure it wasn't a "rattle" (e.g. noise) vs. "vibration" (e.g. feel)...? Did anything actually vibrate while driving, or was it audible only?

Not trying to be an A-hole...just want to clarify your issue for others.

 

My 2014 Sportster 1200 seem to have a kind of a hum vibration at highway speeds from 45 to 60 or so. I guess this is normal for this type of motorcycle... I've started wearing gloves and will soon change out the grips for something with more pad....
Doctor visit today having problems with my left hand being numb and itching. So far I've put about 200 miles on the new to me bike so I hope that's not the problem.... Kind of wonder why Harley didn't cushion the handle bars in some way on the Sportsters. Look like it could have been done pretty easy.

Love my new bike and hope I can keep it.