My orginal thought was that there was something serious as I revved the engine. I could hear what sounded like a big end rattle. It was very worrying as I have not had the bike that long. In the few months that I have owned it from just over one thousand miles to nearly five thousand miles. It has performed well. When I revved or pulled away from lights a low dense noise sounded. I made a video recording on youtube and have included the video. You should be able to hear the noise which sounds alarming but stops when I hold the front fairing which was the cause of the noise.