Having got my F800ST perfect for me, I did a good but silly thing and then changed it for the F800GT. I am still trying to get a screen that works for me. The bike has the tall comfort seat fitted ( to ease my aching hips). The stock screen throws the wind at my chest area and have tried a Puig touring screen and a Givi sports screen. They are taller and cut out the wind to the chest, but create a lot of wind noise around my head. I'm trying to source a screen that is mid way between the stock one and the two screens I have tried. I used a V Stream screen on the ST and wondered to just try one for the ST on the GT. Any advice welcome or indeed if any UK based members have any screens kicking around in their garages etc, I would be keen to hear from you.
I am 5'-8" with a 30" inseam. I have tried several different windscreens of all shapes and sizes. For my height the Puig Screen with their deflector has resolved the wind noise issues well. I did cut some vent holes in the bottom of the screen and this has helped to prevent pulling more engine heat upward.
I just finished a 1,200 mile ride with temperatures that ranged from 60 to 85 F with speeds up to 80 to keep up with traffic in Chattanooga......I had no helmet noise issues (wearing ear plugs). The wind blast from the top of the screen hits the top of my helmet above the visor.....so I don't get much cooling air into my helmet, and I have to crack open the visor a bit when my face gets hot.
6 feet 2 inches. Unfortunately with either the Puig or Givi screen fitted, it throws the wind directly at my crash helmet. I have changed my ear plugs which has helped a bit. Puig screen is solid and Givi screen has vents like the BMW original screen. I haven't noticed any difference with regard to the minimal engine heat issue you mention.
I had a MadStad on my F800GT and it worked well - still some noise in the area of the top of my helmet. However no airflow to chin vent of the helmet. But overall worked OK. So I traded bike for a different brand, so windscreen research all over again! Wound up going with a taller touring windscreen but had the problem you are describing - wind off my chest but too much turbulence around helmet so too much noise. I added a cheap X-Wing from Amazon with the though "if it works I'll get a better one". Wound up with it at just a very slightly steeper angle than the top of the windscreen and it made a significant impact on the noise. Wind noise was eliminated but tremendously reduced. I can now ride at interstate speeds without ear plugs. It's not perfect but have had it for several months and almost 15,000 miles so happy with it. When I first put it on I fiddled with the angle a couple of times but haven't since. most raindrops go over but the very large rain drops occasionally come thru and smack my visor. Only see those on the outer edge of a large thunderstorm which I try and avoid but sometimes there is no place to stop and just have to keep on going! At that point wind noise and rain on my visor are very minor concerns
Wow......6ft-2inches puts your head far higher on the F800GT than my noggin is. The stock screen put the wind right at my chin, and I can understand the wind issue you are having......it is really bothersome once you are out of town and on the highway.
I really don't think any of the available screens will get the wind up over your head like it can for me.
The Madstad windshield may be your only hope - or perhaps you should get a really short windshield and hope the bike acts more like a "naked" bike for you can gets the wind down really low on your torso. (I cut a stock windshield down to the level of the bodywork and rode with it one summer......it wasn't too bad and I even went on a 1,400 mile trip with it). A short windshield offers very little weather protection - but it may be a reasonable solution if you ride primarily in good weather like I do. You might try taking your windshield off and going for a ride and see if the wind is tolerable for you.
Adjustable spoilers have helped me before and the Puig 6319 worked wonders for me on my new F800GT. For you it will deflect some wind off your chest for sure. Besides that at your height I don’t know what else it will accomplish.