I saw another post on the subject. The two things that came out oit were A few rear bearings have gone bad. So check bearings and align wheel so belt tracks center of pully. If the belt is rubbing somewhere you should be able to see some marks on belt.
That is your belt brother.
You need to have it adjusted.
If you look at your belt I would bet money on it that your belt is rubbing on the far left side of your rear pulley. Until you can get it re-adjusted simply spray a little bit of WD-40 of the left side of the rear pulley and the noise will go away.
I have a buddy looking at buying the Raider and so I was checking out the forums to learn more about it. I ride a Kawasaki Vulcan 2000 and have 55,000 miles on it. Our forums have had much discussion about belt noise and wheel alignment. Kawasaki finally posted their response to the issue.
The say the VN2000 belts are designed to ride against the outside of the pulley (some were adjusting the wheel so it rode in the middle) when the wheel is properly aligned. The pulley and belts occasionally polish each other in such a way to generate noises. MaKaw's advice was to either live with the sound as it does no harm (except possible embarrassment) or to remove the belt and use steel wool or fine sandpaper to 'retexture' the side of the belt and inside side of the pulley. This will probably stop whatever resonances are generating the sound.
My belt occasionally makes a squealing grinding noise while accelerating in 1st & 2nd and when coasting to a stop, but about the time I get irritated enough to fix it, it goes away.