Was a bird nesting in it?
Ray, I'll offer one thought. I learned this, the hard way.
At one point, I put by bike on a front stand. I did it just to see if my stand (pit bull) was strong enough.
My stock bike had a plug, in the steering stem, bottom side. To get the peg in place, I had to remove the plug. Of course, I did not remember to put the rubber plug back in place.
At 70-80, and only there, the bike made a sound as if I were blowing across a bottle top.
It might be worth checking as you could cover that hole with a piece of tape, just to see if it helps.
Your clutch noise is normal.
Well, a video (+ audio) is worth a thousand words. I do hear what is almost a "tone" and could tell the short several times you pulled in the clutch starting at 19 seconds (you can see the tach jump too). Good job and good idea. The tone is changing pitch with RPM, so this is not wind noise or other such stuff. I can't tell how loud that "tone" is from the video, although to me it doesn't sound loud. I have not noticed such a sound on mine before, so I am not going to declare it "normal" at this point; but it could be (plus my helmet is loud AND I wear earplugs/earphones). Very interested to see what others say.
Your problem is this: If it is truly related to speed, then it probably can't be the clutch or engine (since clutch and engine both see RPM, not speed). Those would produce a similar sound at various speeds in each gear. It could be the differential or transmission, which DO see speed. With the differential, when you pull in the clutch, although the differential is still spinning, it has no power load on it anymore (the load goes backwards) and that could make a sound from it disappear.
I am perplexed at the moment. How OLD is the differential oil and have you checked the level? (Long shot, but hey, just another thing to eliminate).
Check the exhaust header bolts to head,sounds to me like a possible exhaust leak around that area.That might explain why it goes away when you pull in the clutch,engine goes back to idle.
Just a thought.
Is this sound something started recently?
Have you pulled the Drive shaft to see how much lube is still left on the splines after eight years? They come pretty dry from the factory. That howl sure sounds like gear whine. Just asking?
The only curious thing was twice, when I had my cellphone on the accessory charger, when I turned of the ignition key, it "blipped" on and off about 3 to 5 times before staying off. Weird, but it only happened twice.
That happens with certain electrical add-on accessories, like LED lighting on the turn signals. On mine, it will go crazy if I have any flasher operating (or maybe just the emergency flashers) when the ignition is turned off.
No. And I suspect that it has never been done. I will research the "how to" and do it myself.
Thanks for the tip!