I have the same problem with my Dead Center Fairing, but mine is rpm based not speed based. At about 3000 rpm (give or take a few rpm) my fairing shakes/vibrates enough to cause the weather cover for my stereo to close and rattle. The Klock Werks windshield also vibrates and chatters.
Thanks Resslej. I've always admired your scoot and the mod work you've put into it. Great looking bike!
I'm fairly convinced that it's an RPM issue and not a tire issue (I'm going to fire it up on the kickstand tonight and find our for sure - never thought about that til now) but its definitely happening lower than 3k. Ironically, the thing is solid as a rock at highway speeds, no wobble, no rattle, no buffeting with Curt's lowers.
Since you've done quite a bit of work, do you think my weights idea has any merit or should I throw that right out?