I personally thought my first buell was ready to explode at any time till I got used to the agricultural type sound being emitted from its internals(stems from jap bike background) once I came to terms with that I went on to put 30k plus miles on it and have removed the part of my brain that hears that frequency. are you sure its your mains or just another of erics masterfully mysterious oddities designed to provide visceral satisfaction to those who go to the beat of a different drum. all my buells have been loud, you don't notice the noise as much on a Harley because they all have wide open strait pipes and are cant idle