I just bought my 2012 S40, I have 150 miles on it so far. Right from the start I noticed a very loud whining/rubbing noise when I would decelerate or coast, it's constant regardless of the engine speed, and sounds like the final output shaft to me. I turned right around and went back to the dealer, who rode the bike for a minute and told me it's normal and once the bike is broken in it would go away. Well, I rode the bike for about 50 miles, and it just got worse. It is LOUD, especially if I were to coast from about 50 mph. Like a 'yang-yang-yang-yang' sound. It's not a sound made by the pulley and belt teeth meshing, I don't think.
So I went back to the dealer, told them this is unacceptable. First they insisted it's due to the break-in, but then another mechanic said it was because the belt wasn't tight enough. Personally I thought the belt was too tight to begin with, but they tightened it more. (I didn't know about that plunger in the tool kit, and I've read here that it's not good to go by that, but at the moment the belt is so tight only the first mark on the plunger shows.) Anyway, tightening the belt did make the sound go away, somewhat. I really think something's wrong with a bearing or.. I donno what.
Is this sound I'm describing normal for the S40? Or all belt-driven bikes?? The dealer would have me believe all bikes make this noise. I know better.
I'm going to try and record the noise with my cell phone in my pocket to see if it picks it up, then I'll try adjusting the tension of the belt and slacken it some. Judging by the 90 degree twist video, mine is way too tight. I can pluck mine like a guitar string.