When I test rode a chieftian last fall when the demo truck came. Mine did not rattle or buzz. But one of them did. One rider mentioned it. I also took one the dealer got a month later. That was quiet to. So I think you got the bad one. It is an awesome bike. I will probably get one someday. Just waiting for all the accessories to be available. My bike is all decked out.
I found the problem! As luck would have it, I started noticing a buzz-like rattle coming from the fairing and it got worse when I lowered the windshield on the Chieftain and when giving it gas. I took it to the dealer and they removed the fairing front and zip-tied all the wires and went over everything. When I got it back the buzz/rattle was still there and rode it a couple of days, but it bugged the hell out of me so, while riding, I reached out and pinched the black plastic brow right over the instrument panel and the buzz/rattle stopped. I took it back to the dealer and described what I did and they found the rattle between the two plastic pieces in the inner fairing at the brow. They used double-sided tape and tightened everything and now there is no sound at all. In fact, it sounds tight. Hope this helps all who have buzzing/rattling in your Chieftain fairing.