CL350 Metal on metal scraping noise

[noexit]

My CL350 started making a raspy metal on metal sounding wirring noise today about an 80 mile ride. The last 20 or so before the noise were at 70 mpg freeway speeds. I down shifted and slowed for a freeway interchange and on my way back up to speed, the sound started happening. There was nowhere to pull over, so I had to continue like that for another 5 miles. When I pulled in the clutch, the nose would change, but continue with my rate of travel, rather than engine speed. When I exited the highway, the noise continued for a second, then stopped. I can't get it to happen again.

When I got home, I drained the oil and removed the clutch cover and clutch, but I didn't see any metal in the oil, and everything on the clutch side seems normal.

Any ideas?

 

[Big R]

Could it have been the drive chain?

 

[noexit]

That was where I was going to go next, but it's easier on this bike to drain the oil and pull the clutch than it is to remove the drive sprocket cover. Why couldn't they put the exhaust on the right?