I have noticed a what i can describe as a sort of a howling noise. Kind of like the wind being pushed through a gap making a howling sound. It seems to be generaly towards the rear wheel and Primary cover area. When reving the Engine up the little noise becomes more noticeable. Apart from that all else seems fine. I remember noticing this ones before and then it was not noticed again. But for some reason it has reapeared again. Is this something i need to be concerned about? Has anyone had a similar experience? I like to hear from you.