Really loud whirring
 

I guess it's the belt. I can't tell when I'm riding - it comes from the engine, or I guess the belt. It whirrs whenever I'm not accelerating. When I'm decelerating, it's loud - comically loud.
It's a new 2018 S40 - 150 miles, and whirred from the start. The agency mechanic says it's normal. eh
I'd like to try to figure out what is wrong, before putting grease or anything on the belt.
Thanks for any leads.
Lolocowboy

I have the same noise problem - the description here is almost identical to what I'm hearing. The shop owner thinks it's the belt and suggested polylube (what some Harley riders use) or lock-ease. I sprayed lock-ease on the inside perimeters of the rear pulley and waited for the isopropyl carrier to evap then rode. It made things worse by adding a clacking sound. I read more entries on the HD forum and several senior riders suggested NOT using lube but wiping down the belt and pulley with a damp towel. I washed off the graphite and dried the belt. Now I'm back to the whirring / scraping sound. Is there a cure? The bike is a 2011 LS650 with 1270 miles on it. It sat unused for extended periods. I am swapping out the front and rear brakes (using EBC organics) so I am hoping the mechanic will check the belt tension and alignment. It could also be the rear brake making the racket (doubtful but possible) but even if not I want to know the condition of my brake shoes before riding any distance. It's tough to tell if my front pads are worn or are supposed to look kinda thin (compared to my Royal Enfield) so I am replacing those too.

Anyone know of a cure for the truly annoying scraping sound? Or perhaps a way to definitively diagnose it?

TIA

Whirring and more sounds
 

I found the answer to my problem. It's the speedometer. If I press down on the speedometer while I'm riding, the sound goes away.

Faster Miles Per Hour!
 

That is funny! I'll give it a try. My tank vibrates noticeably so it wouldn't surprise me. Thanks for posting and greetings from a very steamy NYC.
PS - did you find a solution?

Whirring and more sounds
 

Oh sure: Take off the seat; take off the gas tank; see if the gasket is the problem; if not, check the electronics gadget that is hooked up on the gas tank; I have no idea of course how to tell that; check to see if I can see other connections that aren't tight. So in brief, no, I have not found the solution yet. First I have to take the gas tank off though.
Before anything I'll check the speedometer cable that comes out of the gas tank and that goes into the engine. That's the easiest.
I sure don't want to be riding on from now on with a piece of duct tape holding down my speedometer.