About two months ago I noticed a subtle rattle when accelerating while in the 2200 to 3000 rpm range. This thing has been making me crazy. I checked the quick detach windshield and quick detach back rest (a favorite for rattles). No luck. Moved on to check the exhaust flanges and heat shield clamps. Still rattling. Checked mirrors, tool bag contents, and every bolt on the engine and tranny that I could find. Yesterday, I was cleaning the bike and noticed a loose nut on the license plate frame that holds the plate in place at the top. Glad I found the problem, but needed a seven hour therapy ride today to get over it.