Ok it started with a low hum while coming down from higher RPM. Just a slight hum. Now it starts out the same but last time out, as the bike warmed up, the noise became constant and quite loud. Nephew said sounds like a cooling fan. Has anyone had alternator bearings fail on these. 45k miles and it is a pain taking that tank off and of course there is 9 miles down from a full tank. Just my luck. To me it started out like air being sucked through like an air box lid that was loose or missing an o-ring gasket.