This is a pic (hopefully) of a 'screen' I fabricated. It's basically a standard screen with a MRA touring screen sitting about an inch on top. The idea behind this is to encourage a cleaner laminar flow of air over the MRA screen, I have a theory that the negative pressure behind/under conventional screens causes the airflow over the screen lip to swirl -which can get bad enough to cause buffetting. This new arrangement should create a stream of air under the MRA screen and fill-in the negative pressure zone and hopefully prevent the swirl effect. If it doesn't do a good job there is plenty of scope to adjust the height/positioning to see if it makes a difference, it's early days. Once I get the height/position right I'll deal with asthetics.
I tried exactly that using the Yamaha touring screen and some 1cm long spacers! Great minds think alike, eh? Ran with if for a few months. Didn't work!
There's more to this than meets the eye. I don't think it's the negative pressure that causes the problem (if you've ever ridden a Gen 1 FJR, you really feel it. It's like a hand pushing at your back, but actually it's the low pressure in front pulling you forward), so it's probably a combination of problems. First, there's the height of the entire fairing - it's an inch or so too low, then there's the mirrors which seem to deflect turbulent air all over the shop (taking them off can improve things) and then there's the width of the screen which is too narrow.
And of course, there's the size of the rider. The Japanese seem to aim at the average person for Japan, but I'm 6'1". I'm outside their envelope.
Doing what we've done certainly makes a difference to the amount of wind pressure, but the screen was just too narrow to be properly effective and that slight flip did seem to aim the turbulent air directly at my helmet vents which meant it was noisy. I bought a Givi touring which is wider and that made a bigger difference to my riding comfort. With the standard screen, things got weird at 80, but now it's 95. I also notice the Fazer is very sensitive to which way the wind is blowing, not from a stability point of view, just comfort wise. 3/4 sidewinds seem to affect it really badly, but head on, not so much.
Wind protection is a nightmare on bikes if you're a large bloke. I suspect Japanese manufacturers rarely put bikes like the Fazer in wind tunnels. Even my ZZR, which spent a lot of time in a wind tunnel during design, is atrocious without a massive touring screen, but then again, it was designed for top speed not user comfort.