Attempts at trying to solve buffeting behind motorcycle windshields have often been disappointing, but here's a couple of very encouraging success stories:
StolSpeed vortex generators on a Ducati Multistrada
With the roar flaps, F.Fabbri screen, and Aztec spacers, the silence was golden. Unfortunately, that bubble of calm air was not very wide. If I moved my head just a couple inches left or right, once again my helmet would be thrashed with turbulent air and my ears would be tortured with the deafening roar. And if I happened to be passing a large SUV or truck, the bubble of calm air would mostly disappear.
To better understand where the turbulence was being generated, I covered my windscreen with homemade telltales (pieces of yarn taped down so that they show the flow of the air) and rode around at various speeds. I realized that a significant source of the turbulence was from the screen pushing the air diagonally upwards to the left and right -- at the correct angle to hit the bottom of my helmet when I leaned slightly left or right.
So I mounted StolSpeed vortex generators with 30 mm spacing at 15 degree angles to the streamlines indicated by the telltales. Wow, what an unbelievable difference!
I can now move my head almost a foot in either direction and stay in smooth air. Who knew a handful of tiny plastic vortex generators could widen the sweet spot by so much?!?!
It took a few tries, but your vortex generators fixed the buffet problem better than I thought possible. Once I got the locations right, the generators changed the buffet I was experiencing on the top of my helmet to a smooth laminar flow. I still get a pretty good wind blast across the top of the helmet, but it is smooth rather than rough, almost like the difference between swimming in a current vice swimming in surf.
I should note that I also filed the windshield mounts to decrease the angle of attack of the windshield (I brought the top back about an inch). Changing the AOA alone did not fix the problem, adding the VGs once I changed the AOA made all the difference. I discovered that dropping two sets of the VGs an inch below the others significantly changed the airflow (for the better). I wouldn't have predicted that, but discovered it when a linear arrangement didn't work as well as I wanted.