I test rode a 2001 Fat Boy with a 95 big bore the other day. bike appeared to be perfect one owner, but at around 70 mph, there was a very hard vibration. I understand that softails can have a "buzz" but this seemed more then that. or is this something common in that year range?

 

and just for the record, i have owned a sportster, dyna and street glide before and have never had this experience.