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OK, well now I'm just plain curious. Since I bought this beast, I've mostly been on twisty roads around the lakes east of Phoenix, but as soon as it gets below 110 degrees around here, I'm gonna go play on the freeway and look for trucks. I'm coming off of a Kawi Concours, which is no lightweight, and has plenty of wind protection, and would heel over like a 12 meter racer in a strong cross wind. Dirty air, though - nothing. Passing, getting passed or following trucks was completely unnoticeable, one-up or two-up. Come to think of it, I did log a fair number of freeway miles on the day I rode the GTL home from the dealer, and I remember being behind or beside at least a couple of trucks as I was doing lots of shifting and varying engine speed. I don't remember noticing any additional puckering from the aerodynamics. Maybe I just have steely nerves and superhuman reflexes - no, I've seen the videos - that's not it. I'm definitely gonna go play on the freeway, though.
 

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OK hre's my view after 50 years of riding (holy smokes): The K is built to be an agile high speed tourer so you'll get some sensitivity to dirty air and cross winds. If it bugs you consider a different shield. I went with a Cal Sci large which give me the same protection as OEM 1/3 up when it's all the way down. The improved profile makes a big difference. It still responds to bad air but not nearly as much. If it didn't dance a little in turbulence it would be a slug when you need to throw it around. Just accept it as part of the total performance package.
 

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Some say if your bike is bad in dirty air change the tire pressure. Some say remove the Aero Wings if installed. Some say run this windscreen or that windscreen. Some say loosen your grip. Some say tighten your grip. Some say you need more weight. Some say you need more rake. I say trying to eliminate this anomaly is like pissing up a rope. Get over it. Live with it. You ain't gonna fix it. :)

Duane
 

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My GT is one of the more stable bikes I’ve ridden. Tire pressures should stay as indicated by the mfr. 42 psi. If I encounter an situation where the turbulence is bad, I can either back off the throttle detail or speed up to get out of it.
 
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When you are in multi-lane traffic there is little ability to distance yourself. For my bike, the issue with simply following or passing a single vehicle is manageable and actually fairly minor when riding 2 up. Frankly the bike has handled pretty well in fairly heavy wind on 2 lane roads as well.

This becomes an issue for me exclusively when I am surrounded by other vehicles running 1 up at highway speeds - heavy, multi-lane traffic. Sorry if this annoys some but I'd like to make an effort to mitigate it some vs just accepting it or abandoning the bike.

Curious if anyone has experienced better performance with the bags loaded (ballast). I have actually considered removing the front floor boards since they basically act as an air wing. I really don't use them anyway.
I have set the bike for 2 up when riding solo on my GA. This helps but does make the ride a bit harder. Removing the top box was the one spectacular improvement. Removing the floor boards on the GA looks to be quite a mission with the rear bolt and I like having them, so I placed some very thick rubber washers under the boards to lift them up and actually make them aerodynamic, as a trial. I may have imagined it but it did seem to help but only marginally. I'm keeping my floorboards. It may be possible to remove the boards and put highway pegs on the floorboard framework but they would stick out a fair way. I thought of just using the framework but the engine would leave only a tiny bit exposed to get your feet on.
 

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turbulence or dirty air as it's called, is created by things you have no control over. Your bike's shape as it passes through air is only a small part of the puzzle.
Accept that it sucks to ride through and just enjoy the bike. I miss the fairing of the k16 as I ride a GS but I enjoy the GS for other reasons.
 

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I will apologize in advance if I am lighting a fuse - hopefully not. I have read through some pretty contentious threads here related to this. It seems to be generally accepted that the K bikes (especially the GA and B) get pushed around in dirty air. This is not meant to debate the extent of that -- I'm interested in feedback re: what setup has been most effective in reducing it.
I have an '18 B. Fairly new PR4's, 7Jurock 18" screen, and just added a Shad 58 top case that I run collapsed unless its parked w helmets in it. I have found the bike to be absolutely rock solid in any situation other than 65+mph in multi lane traffic. In dirty air, it literally becomes a different bike. As has been mentioned, it is not felt as a "wobble" in the bars but the bike just demonstrates a side-to-side "twitching". I had the same issue prior to adding the top case.
Running the screen down and tires near max inflation seems to help but its still there and becomes an issue if ambient wind picks up any amount. I don't normally heavily grip the bars but maybe as this thing starts to wiggle around I do it unconsciously so will keep that in mind. Also per threads here, will try riding with more pre-load on suspension.
I love this bike and don't typically have to ride in multi lane interstate traffic, but its hard to avoid it some times so I'm looking for suggestions to manage it better.

What has proven effective for others in reducing the effects of this? Screen width, tire pressure sweet spot, anything short of strapping a duffel bag on the pillion?
Check out California Scientific, calsci.com. Read the testing and airflow research, it’s logical and proven to reduce wind buffeting at speed. I switched several years ago on my 2013 GTL, what a difference. Hope this works for ya. Ride safe.
 

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I read an interesting take here on the forum, linking the instability to air pressure, the windshield creates an area of low pressure as the air goes around the windshield, which reacts kind of like the lift under a wing. I hope I'm getting the OP's theory right. It was suggested if you have a windshield with a vent in the middle, it would reduce the low air pressure pocket that causes the instability.

I feel the instability at high speed on my stock GA and in my case don't feel it causes any loss of control. I've tried hard lane changes at high speed and the bike reacts the way I expect.

I agree, my GA is such a great bike in all the situations I've been in, it's just about perfect for me.

This company makes lips that attach to the top of your windshield to give you that air hole. They say that the turbulence can be stopped by splitting the wind and stopping the negative air building up behind your windshield.
 

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Mr.Fix It
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@MVP , everything I've read say those "lips" work. What they don't say is it's the ugliest farkle every added to a motorcycle; e.g. looks jury-rigged... :)

Duane
 

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Mole999 has the right answer. I really don't think this bike is any more susceptible to buffeting around than any other big touring bike. Think about it - the bike weighs over 700 lbs and is mainly aerodynamic. You weigh, well, what ever you weigh but from the torso up a fraction of what the bike weighs with the aerodynamics of a door. You get buffeted around much more than the bike and when you lock on to the bars with a white knuckle grip, you transmit all the buffeting to the bike. Next time you're in that situation, release your grip so that your fingers are encircling the grips but not touching them. You're going to get buffeted around as much as usual but the bike will be tracking properly and not doing the dance it did with your firm grip on the bars.

If it feels insecure to loosen your grip on the bars it's probably because you're not locked on to the bike with your knees and lower body as solidly as you could be. It's one of the first lessons you learn at a good track school is that riders are prone to all manner of bad inputs during the more exciting moments of the ride and the more loose your grip, the better you can feel what the bike is telling you and the less you'll communicate bad things to the bike.
 
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Lots of knowledge stated above. Timely conversation for me as well!

Coming off two GTLs, I got some seat time on the B yesterday across the fruited plains... the B, solo with Aeroflow x-tall (6’-3” height) is way less stable than the GTL. I attribute to the floor boards. They increase lift with the passing traffic. Proving this impact, I decided to wedge my feet and tip them in on a few passing by semis( not actual passing), and I’d say the turbulence was more GTL like. Same windscreens, helmets, gear etc. Amazing what nuances you start to learn and fart around with when you have some seat time.

BTW... this bike kicks A-S-S-!




Sent from my iPhone using Tapatalk
 
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This company makes lips that attach to the top of your windshield to give you that air hole. They say that the turbulence can be stopped by splitting the wind and stopping the negative air building up behind your windshield.
It may create a bigger hole in the air, but it won't decrease the low pressure area behind the windscreen, it will in fact increase it. Even their own drawings show that. By punching a larger hole in the air you can mitigate back pressure by putting more of the bike in that envelope of low pressure but you will do so at the expense of aerodynamics and you will in fact create more turbulence (somewhere). The CalSci hole and the DIY hole solutions are a better solution for laminar flow as you have airflow following the inside face of the windshield creating a clean airflow as it meets the air coming from the outside flow over the windshield. You can actually feel it by sticking your hand up into the airflow, the demarcation between no pressure, and clean - faster moving air is very distinct, and the flow is very smooth.
 

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floorboards as wings, any aviators out there want to give an idea of how much lift might be experienced. I could see it applied to hydro application, but can't see myself that it would generate anything noticable (happy to be proved wrong)
 

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floorboards as wings, any aviators out there want to give an idea of how much lift might be experienced. I could see it applied to hydro application, but can't see myself that it would generate anything noticable (happy to be proved wrong)
Basically very little meaningful lift. They would first have to generate enough force to counteract their own mass. Lets say that each floorboard could generate 10 pounds of lifting forces under perfect conditions.

They are sitting in the dirty air coming from the tire/fender/bodywork.
They are symmetrical in placement.

There is no low pressure area on the top of the floorboard as soon as you put your foot on it so it will not act like a traditional wing, you only have the pressure created by the mass of air you are moving through and the surface area of the floorboard --- and then, only really in the clean air.

Being located near the center of mass means that they have very little mechanical leverage to impart a force.
To cause instability you would need the entirety of the lift on one side, then the other, thats 10 pounds of force on a 700 pound motorcycle plus rider(s) and gear.

How is it different than sticking your feet out on highway pegs? Yes your foot is smaller but as an experiment, do you feel lift when your feet are on the highway pegs?

Two different riders of different weights could have far more effect as their mass is further from the center of mass.

If you want to look for problems arising from aerodynamic forces look to the rear of the bike (the front is identical across all models). Look at the picture I posted, the differences between the GA/GTL are obvious and the B is just the GA without the topbox.
 

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Anything sticking out in the relative wind causes parasite drag which increases with the square of speed. That's why it takes more power to go from 100 to 140 mph than it does to go from 40 to 80 mph. A lot more power. Anything that creates lift or downforce also creates something called induced drag - you don't get lift for free - and lift is a factor of several things: the size and shape of the "wing" and the angle of attack (to the relative wind). Higher angle of attack means more lift and drag up until you reach the critical AOA when all lift departs and you're left with nothing but drag. Every kid that's ever stuck his hand out of a car window has demonstrated this. Without some rigorous testing you'll never know how much lift (or downforce) is being generated but you can bet there's plenty of drag from all those things sticking out in the wind. At really high speed, it makes sense to me to more concerned about asymmetrical drag than lift on a big bikeapotomus like a 1600.

I took an interesting photo several years ago that's posted on here somewhere. It shows the difference in what a K1600GT is pushing through the air vs. my S1000RR (remembering that drag is square of speed thing):

 
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