As far as I can make out this is a common problem with Harley Davidson belt drives. It seems correct tension and rear wheel alignment are very important to eliminate belt noise. Keeping the belt clean is also very important and Harleys have a lower guard to help keep grit and small stones from being trapped in the belt.
Some recommend spray on silicon lubricants that leave a dry but slippery finish, but it seems that does not last very long. Clearly any "wet" oil or wax based lubricant should be avoided as that will carry dirt and grit which would quickly damage the belt and the pulleys.
Done both, as in, keeping it clean and using silicone. Doesn't matter. It's the aluminum, which is too soft to stand up to the kevlar based belt! It will eat it like butter! I've driven after rains, when the road is immaculate, dirt and dust free, to only have the noises come back after 15 miles!
To reiterate: the Harley-Davidson sprockets, of which there are many, are made of chrome plated steel. The M3W's sprocket is made out of anodized aluminum. Anodized aluminum is damn hard but it has its limits! Anodization is only a few microns think! It's great for non-stick pans and the Calphalon brand but for this?!
I've also found out that the Poly Oil is difficult to acquire as it was used to address an older problem which has decreased in occurrences. They figured it out and engineered a solution and eliminated a need for this fix, which was a temporary fix at that!
argh!
