Need help with a problem...Have a strange noise on left side of engine when going thru the gears.Sounds like a small fan blade rubbing against something. Happens at the same RPM in all gears. 5th gear starts at 65 mph and quits at 70 mph.Could it be a stretched chain or a loose something or other? I´m not too swift when it comes to the mechanics of my bike.... Thanks for your input...