[Clint]

I still hold that it's a poorly dampened front suspension. The braking exercise would only eliminate that possibility if it was a spring preload issue, not if the damping hardware or oil are insufficient. Changing the tire changed the period of the wave pattern because of differences in sidewall stiffness and tire pressure.

This is very similar to a high-speed wobble (the kind that can lead to tank-slappers), where natural suspension rebound action and inertia set up a standing wave bounce. I'd try heavier fork oil before paying a shop for a bunch of time.