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Post by muss51 on Jun 16, 2008 6:31:03 GMT -5
i have the standard windshield on my grand vista and i notice when i am at speeds of around 65mph that i get a kind of buffeting from side to side. which also seems like a squirm of the front wheel. and now i'm wondering if this is typical of the touring style scoot or if this is my imagination.
also if i put on a tall windshield will the above problem be any worse?
pro's and con's of the taller windshield would be appreciated.
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Post by fufu2wheel on Jun 16, 2008 7:53:01 GMT -5
Taller windshield would not solve the problem of squirmy front wheel, nor helmet buffering..
Cleaner airflow to the helmet would help the helmet buffering, or allow a bigger hole at the base of your windshield to equilize the pressure between front and behind of windshield.
Front wheel squirmy could be many different causes.. diagnose and resolute.
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Post by stewntexas on Jun 16, 2008 11:01:22 GMT -5
One thing you should consider before using a taller than normal windshield. If you get caught in the rain, can you 'scoot' up and see over it?
Trying to see through a lot of rain drops can be a problem.
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Post by gusset on Jun 16, 2008 11:10:26 GMT -5
A taller windscreen MIGHT reduce buffeting, or it might not. It depends on what it does to affect airflow around your helmet. Going from a short to a tall windscreen on my S2 removed the body blast I would get when riding, but in the process it put the rough zone of transition between low/high pressure right at my helmet level, resulting in a fair degree of buffeting. (If I were a few inches shorter it would probably be much better.) I added a self-built extension, raising the upper edge by about 5-6 inches. The zone was pushed further up, reducing the buffeting quite a bit. My solution is, at this point, a "brute force" method that might be at the slight expense of fuel economy or top speed. I wouldn't characterize my efforts as a good example of engineering.  I wish my bike's windscreen had a vent down low, because as fufu2wheel notes, this helps a lot, and likely does so without hurting performance. I've been tinkering with my extension design to try to do this. Seems to help. Buffeting is a complex thing. |
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Post by okie34 on Jun 16, 2008 16:50:09 GMT -5
How would you "vent" the taller windshield. I'm a few inches shorter than Gusset (by your description G!!) and the taller windshield "should" put the slip stream (lack of a better term) right at the top of my helmet.
However, the pressure differences you are talking about being reduced by "venting" the windshield, now that's a whole new ballgame. I'm curious as to where to place the vent? How would you deflect rain? Would you even bother to? Would you try to deflect the "vented" stream upwards to the inside of the windshield?
The S2 250 has the area from the top of the dash to the bottom of the windscreen that appears to be a great place to try and vent since it looks to be mostly decorative and is very good at collecting dust. I'm really curious about this and how it would work without compromising the wind screen integrity.
Didn't mean to hijack the thread!
JD
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Post by earlwb on Jun 16, 2008 17:04:26 GMT -5
Wheel squirm at speed? Hummm....I would seriously check to ensure the front steering stem and forks are not loose. if they are tighten it up before you do anything. Check your rear axle nut and ensure it isn't loose as well. The rear bearings on the right swingarm tend to loosen up causing the nut to come loose. Check your front end as well to ensure the front wheel isn't loose.  |
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Post by gusset on Jun 16, 2008 19:30:07 GMT -5
How would you "vent" the taller windshield. I'm a few inches shorter than Gusset (by your description G!!) and the taller windshield "should" put the slip stream (lack of a better term) right at the top of my helmet. However, the pressure differences you are talking about being reduced by "venting" the windshield, now that's a whole new ballgame. I'm curious as to where to place the vent? How would you deflect rain? Would you even bother to? Would you try to deflect the "vented" stream upwards to the inside of the windshield? The S2 250 has the area from the top of the dash to the bottom of the windscreen that appears to be a great place to try and vent since it looks to be mostly decorative and is very good at collecting dust. I'm really curious about this and how it would work without compromising the wind screen integrity. I'd love to learn the answers to these questions and issues, myself. For a while I was tempted to try putting a vent near the bottom of that large parcel of acreage you mention; since it's below the upper windscreen retention screws, I reasoned that it shouldn't impact the screen's integrity, and the air flow should be directed upward by the shape of the bodywork. I hadn't decided about rain being problematic. In the end, though, in a fit of rare common sense, I decided that I am not willing to experiment on my $170+ windscreen...that's the main reason I've limited myself to "add-on" hack-jobs. ;D One of these days I'll post some pics of my efforts on my site and solicit further ideas and feedback, but I plan to wait until my level of craftsmanship rises. |
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Post by okie34 on Jun 16, 2008 21:34:17 GMT -5
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Post by pedez2000 on Jun 17, 2008 1:06:26 GMT -5
try going wider. mrp has them and i have some comming.
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Post by fufu2wheel on Jun 17, 2008 6:47:55 GMT -5
It doesn't necessarily need to have that big of a vent at the base of the windshield. You could just try carving out one or two triangular holes pointing forward on the windscreen, sand off the leading edges to allow better airflow than square edges. Like the side air inlets on a 1997 Honda VFR:  |
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Post by okie34 on Jun 17, 2008 9:33:36 GMT -5
Like Gusset, I don't think I'm quite ready to "carve out" anything. However, what's been said has merit.
Since Gusset and I are talking about a specific vehicle with a unique windscreen set up, I think I may start a different thread or simply drop this line altogether.
On that note, for a windshield that doesn't have a lot of decorative space, I think the solution I posted above would be a good one. It's relatively inexpensive and it does what it's supposed to to. There are other options out there for folks who want to DIY. You can get a Goldwing vent and cut the holes and adapt it in. In any case you look at, unless the windshield is custom made or OEM from the factory with the vent built in, your going to have to cut the hole or have someone do it for you.
There are places that do vented windshields. However, they do them for the HD's and GW out there. There are very few that do this for scooters (I haven't found one yet). Yes, MRP has windshield, but I didn't see where they were "vented" or model specific. They are add-ons that can be placed a bit higher on their mounts to create a "vent effect" but that's placement on not something that will help an integrated windshield.
That being said, I'm not an engineer and my knowledge of fluid dynamics is limited to Thunderstorm development and is rudimentary at best. However, what's the goal of venting a windshield? To alter or disrupt the current of air to produce less buffeting to the rider. Don't defeat the purpose of the windshield trying to get around that. Any flight folks out here that can give a little better answer?
JD
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Post by ScootCouple on Jun 17, 2008 10:11:46 GMT -5
I think I experienced the same thing muss51 did with the buffeting at higher speeds with my GV.
I felt it was the wind hitting my shoulders going past the narrow windshield at high speeds and making my body/arms wobble which in turn acted on the steering. What made me determine that it was wind buffeting was when I drove the same road at the same speed tucked (head down behind the 'shield and elbows tight to my body) I had no problem with wobble at all. moss51 - do earlwb's checks first or have your dealer do them, for safety, then try the tucked drive and see if it still happens - be sure to let us know.
This was the push that made me purchase the taller and wider Givi windshield. Air flow and noise are smoother now, less buffeting from gusts and oncoming vehicles and because the airflow is smoother I went from 63mpg to 65mpg. It's now like riding a convertable, where the air 'fluffs' around you from the back and sides. (Sorry, couldn't figure out a better word for it.)
The difference in ride was what made me deterined to find a windshield for my wife's Lance Vintage.
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Post by bobpt on Jun 17, 2008 22:50:17 GMT -5
The taller windshield might help a little bit with the buffeting. You also need to consider how far away from the windshield you are sitting. The air flow around the sides of the shield may be collapsing in on you where you sit.
I have a windshield on the Pegasus and I sit about a foot behind it and I get virtually no side buffeting but I get a powerful negative pressure area between me and the windshield because there is no venting.
The Reflex does have venting through the front cowl and although it helps cut down on the front negative pressure area, it doesn't eliminate it. On the Reflex, I sit about 2 feet behind the windshield and I do get some side buffeting. If I inch myself a bit closer to the windshield, the side buffeting is almost negligible so I am assuming the airflow is now going by me. However, I am sitting on the tip of the seat when I am that close and my crotch doesn't like that for too long.
I just replaced the standard Givi windshield with the taller one and that puts the air stream just over my head. That wind noise has been severely reduced and I can now hear myself think. Time to start using the MP3 player on the short road trips.
Bob
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Post by bobpt on Jun 20, 2008 22:18:30 GMT -5
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Post by pb12mm on Jun 20, 2008 23:24:42 GMT -5
What scoots out there come with vents from the factory? If I had an example, I may be willing to try a DIY. I hate the helmet buffeting. I am at the perfect height for it. If I scrunch down, it is all but eliminated, but I can't ride like that.
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Post by joernct on Jun 21, 2008 7:28:08 GMT -5
There's a guy with a video of his Burgman on YouTube that shows the vent. His YouTube name is DuckScooter. Search for that name and you should find his videos.
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Post by muss51 on Jun 22, 2008 7:21:49 GMT -5
last Monday i decided to give a taller windshield a try. and see if i would like the difference.so i ordered one from twisted throttle and it's been all but a week now and no shipping info yet.
did any of you ever order from them?
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