Anyone tried cutting down the stock windshield?

[dcstrom]

I've been looking at replacement windshields for a while, and from all reports the ones that work the best are the bigger ones... however I don't need all that protection, and bigger shields can be a bit of a liability on dirt. I just want the buffeting to stop. So I figure that, rather than buy a medium-size aftermarket screen that may or may not work, or buy a large one that I don't really want... it couldn't hurt to try cutting down the stock one first.

Anyone done it? I figure at least 2" needs to go for it to make a noticeable difference, maybe more.

Trevor

 

[Z06]

Should be no problem trimming it down. Don't cut it if the screen is cold. If needed warm it up to 80 degrees or more to reduce the possabilty of cracking it. Same applies to drilling.

 

[jajpko]

I've been looking at replacement windshields for a while, and from all reports the ones that work the best are the bigger ones... however I don't need all that protection, and bigger shields can be a bit of a liability on dirt. I just want the buffeting to stop. So I figure that, rather than buy a medium-size aftermarket screen that may or may not work, or buy a large one that I don't really want... it couldn't hurt to try cutting down the stock one first.

Anyone done it? I figure at least 2" needs to go for it to make a noticeable difference, maybe more.

Trevor

Cutting the stock one will lose the lip. Don't know if that is good, or bad.
Have you tried riding with no shield? That should tell you if your helmet may be causing a problem or if a lower shield would be enough to take the wind off your chest and not the helmet. ?

 

[dcstrom]

Cutting the stock one will lose the lip. Don't know if that is good, or bad.
Have you tried riding with no shield? That should tell you if your helmet may be causing a problem or if a lower shield would be enough to take the wind off your chest and not the helmet. ?

You're right - I had been MEANING to do that - but forgot! Maybe try it this weekend...

 

[snakebasket]

Check out the WASP thread on ADV, he cut down a tinted screen for the S10, looked pretty good.

 

[Motowalt]

Check out the WASP thread on ADV, he cut down a tinted screen for the S10, looked pretty good.

That's how I'm thinking of going....but I emailed CalSci to ask if they have a 2" shorter tinted version with the hole (as Wasp recommended) and never got a reply from them...

 

[wantajustride]

dcstrom.

I had a severe case of the head bobble thing goin' on with my Wee. I took the stock screen and cut a good size hole in the lower center portion of it. Buffeting reduced tons to almost nill. I started out using a cut-off wheel with the air compressor at slow speeds. That didn't work so well.
Then tried a hacksaw blade without the handle and just gripping it with a gloved hand. That worked well for me. Just took my time. I made a template out of paper of the desired shape then traced the outline to the screen with a sharpie, and followed the lines with the saw blade.
Before I did it I checked the price of a replacement screen in case I completely chubbied up the whole thing.
Lots of post about windscreen mods on the forums and this one made sense for me. If you can deal with a hole in the screen. Some folks think it's OK looking and some think it looks like fidos arse. Cutting the top lip off the stock screen may look better, but I'm not sure what will happen to the air behind it.
WJR

 

[Carolina Tim]

Theory about flips and lips

I'm considering cutting off the "flip" and the "lip" on the OEM shield. Hadn't thought of punching a hole in its middle (as above), but may do that too, as it should improve (laminar?) flow. Then, I'd supplement the OEM with a bigger, cold weather/long trip screen, maybe the Givi or MRA.

Here's my analysis (at 5'8" with seat in the lower position): The OE screen creates a high frequency vibe/bobble to my Arai XD4 (and also, but to a lesser degree, to my HJC full face "regular" helmet). Moving the screen up only changes the speed at which i experience the buffeting. My (too many decades) long experience with various OE and aftermarket screens leads me to conclude that screens with those concave "flips" to direct the air farther outward (bigger still air pocket) and/or "lips",, those beads at the screen's edge that must have been specd by company attorneys (maybe they're thought to reduce the risk of lacerations in case of a crash?---that both of these design features tend to create turbulence.

My crude tests of this for the S10 were to ride for a while with two different smooth shields on hand that were made for the BMW F650 GS, and that just happened to (sort of) fit. Both of these helped----some. The smaller one yielded the most improvement. One is approximately the size of the OEM, but smooth with neither lip nor flip, the other is no more than a flyscreen, and also nearly completely smooth along its outer edge. Running my bike yesterday both in town and on the interstate (up to 80 mph indicated, very light variable winds) with NO screen, I had NO turbulence, but I did get too much wind flow/resistance for relaxed long distance, high speed riding.

These "tests" tell me that the flow can be cleaned up completely by eliminating a shield, and that the flow can be improved to some degree by using a shield of a different (simpler) shape that is no larger than the OEM.

So at this point, I see no downside to modifying the OE screen, as it's not acceptable to me in its present form. I'll probably start by cutting away the inch or so to eliminate the lip and flip and then test the result before cutting more. My reluctance is that I don't want to botch the job.

Does anyone have ideas about how to cut, sand, and polish to get a decent result? If I attack it with a hack saw, will I be able to sand it smooth? Would it be better to grind away that inch or so against a grinding wheel?

 

[Carolina Tim]

I meant to add to the above that one part of my crude testing methods has been to move my hands through the airflow where it dumps onto my head/chest/shoulders and also where it exits the screen/bodywork/mirrors. I think this gives a lot more information than simply considering how one's helmet and head behave under various scenarios.

I guess there's not much we can do about the dirty air coming off the instruments and mirrors, but they surely are a partial source. If you've road raced or done track days, then you've probably noticed how much calmer things seem without mirrors (at least calmer airflow-- wise, as in my case the calmness quickly vanishes as the inevitably large group of faster riders comes strafing past ).

Doing this on the S10 yields interesting results: It seems that the OE screen churns even the air coming from around the fork and the outsides of the bodywork. (and maybe this is what those Yamaha "wings" address?) But any shield I've tried on the S10 seems to "dirty up" the air coming from the lower areas of flow. The cleanest flow is when the bike is shieldless. I think this observation lends support to Wantajustride's mod to his VStrom described above (hole in middle), but I'll defer to you engineers to explain why.

 

[3putt]

This one will get rid of the turbulence but you catch a lot of bugs on the helmet shield. Makes the bike feel like a motard.

Link on how to build it and the downloadable PDF template:
http://www.yamahasupertenere.com/index.php?topic=3731.0

 

[Checkswrecks]

Trevor - I trim windshields all the time and just did the edges of my son's VStrom. I made the one that you saw last fall from a Burgman windshield. C'mon by if you want and we can do yours, once you know what you want.

Trace the current shield onto a piece of plastic or even cardboard. Ugly is fine and old political campaign signs work great. Mount it with the 4 screws or even tape, then ride and cut till you have an idea of what works.

 

[3putt]

Re: Theory about flips and lips

So at this point, I see no downside to modifying the OE screen, as it's not acceptable to me in its present form. I'll probably start by cutting away the inch or so to eliminate the lip and flip and then test the result before cutting more. My reluctance is that I don't want to botch the job.

Does anyone have ideas about how to cut, sand, and polish to get a decent result? If I attack it with a hack saw, will I be able to sand it smooth? Would it be better to grind away that inch or so against a grinding wheel?

I put masking tape on the shield and mark my cutting line then use bandsaw. Grinder will cause it to melt some, but works. I clean it up after cutting with sandpaper and wood block. 120 grit then finer to smooth out the edges.

Funny you mention using an old screen for the F650GS, I had one left over from my wife's bike by madstad, cut it down to fit and trimmed the bottom to match the stock screen. It is larger than OEM so it is very nice for winter cruising, but costs me about 2 mpg.

 

[Carolina Tim]

Tiger and co.,

Thanks for the tips/info.

I like your little black screen, and I agree that it makes sense to have a small, summer screen and a larger one for touring and winter.

Having just put in 250 miles with the stocker in the low position, I now know for sure something has to give. The only way I could get comfortable with the dirty air (especially above 70 mph) was to move way forward over the tank so that my visor was almost even with the top of the screen. Ugh. The windier it was and the more traffic in my vicinity, the worse the buffeting.

But before I start cutting, I'm going to go back over the thread about the side deflectors.

 

[kywheels]

Took mine to a local plastic shop and they charged me very little to cut it down and polish the edge. I had them cut it about 1/2" above the top bolt holes. It got rid of the turbulence, it now feels like there is no windshield. For me it was a huge improvement. BTW- im 6'4".

 

[Checkswrecks]

Re: Theory about flips and lips

Does anyone have ideas about how to cut, sand, and polish to get a decent result? If I attack it with a hack saw, will I be able to sand it smooth? Would it be better to grind away that inch or so against a grinding wheel?

Hacksaws can work but most people tend to push them, creating cracks. I use wide tape on BOTH sides of the plastic and draw my cut line on that. I also prefer a bandsaw but going slow with a jigsaw does work fine. Use a metal cutting blade and go slow to let the teeth cut, making sure to put no pressure on the plastic. After the first few inches, re-tape the cut behind the blade to prevent the loose piece from vibrating. Cut all the way and don't try to start from both ends of your cut line to meet in the middle.


Once it's cut, I prefer to use a belt sander and sharp file to dress the edge. ONLY ONLY ONLY sand and file along the edge, not across it. Once the shape is right, go to a fine sandpaper. Inspect closely to make sure there are no cracks from the saw and if so, sand those out completely.


A good plastic shop will use a hydrogen torch so that the edge has a perfect glassy finish, but I normally leave it sanded.

 

[dcstrom]

Re: Theory about flips and lips

The mention of cutting a hole in the screen reminded me of the one in the Cee Baileys screen on the Vee - which I like a lot, and which has none of the turbulence of the S10 screen. I think I will have a go at cutting a hole before I trim some height off it. If it doesn't work I can block the hole somehow and I'm back to where I started. Different story if I lop 2" off the top!

A good plastic shop will use a hydrogen torch so that the edge has a perfect glassy finish, but I normally leave it sanded.

I'm thinking a "good plastic shop" could cut that hole for me in a matter of seconds - but where would I find one of those?

BTW Bob, thanks for the offer of help with this - I may yet take you up on it!

Trevor

 

[Merfman]

Learned from my Strommin', another way to get that nice edge on a freshly cut shield is to take a rag wet (but not dripping) with MEK (methyl ethyl ketone)
and make a pass around the freshly cut area. Smooths it out quite nicely. I too used a bandsaw to cut my Strom shield...

Thanks for posting all the trials here gents, I'm readin'... keep postin!

 

[Checkswrecks]

Learned from my Strommin', another way to get that nice edge on a freshly cut shield is to take a rag wet (but not dripping) with MEK (methyl ethyl ketone)
and make a pass around the freshly cut area. Smooths it out quite nicely. I too used a bandsaw to cut my Strom shield...

Thanks for posting all the trials here gents, I'm readin'... keep postin!

You would have to be SUPER careful with this trick. MEK runs as easily as alcohol and if a drip runs across the face of the plastic, you'll have a streak that is an absolute bear to get out. Or worse.


I've seen a guy spend all day getting a new windshield into a small airplane and then totally ruin the windshield while using MEK to clean some sealant from the edge. A single dribble ran down the new plastic. ???

 

[dcstrom]

So this is what we did...

I have a Cee Baileys screen on my Strom. It's just a tad higher than the stock S10 screen but no turbulance. The difference may be in the "letterbox slot" that's cut into the lower part of the Cee Baileys. I figured I have nothing to lose by trying a similar slot on the stock S10 screen, since if I can't fix the turbulance it's getting replaced anyway.

Checkswrecks kindly offered to help me with it, since he's done a bit of work making screens before. The tidy part in the pics is his work, the ugly stuff is mine. When we'd finished with his part, we agreed it "passes the 10-foot test". Well now, it just about passes the 20-foot test!

It's hard to say if there is an improvement from a short ride around the beltway, but I get the sense that it's a bit smoother. I think most of the buffeting is coming off the sides rather than the top, and if that's the case this won't do much.

But if it does I have some ideas for cleaning this up and keeping the screen. It may be that I made the hole too big - I'm no expert but I get the feeling that velocity is more important than volume for the layer of air coming up the inside of the screen. So I'll ride for a while like this, play with the size of the hole, and report back. If it turns out to be a good mod I'm sure others can do a much neater job than me...

I'll post some vids soon showing the difference...

 

[dcstrom]

Here's a vid showing the difference in the 3 stages of "development". I don't know anything about testing aerodynamics but I cut up some old shoe laces and taped them around the boundary of the screen to see if it would tell me anything about air flow. I think it did.

First, in all three cases, the pieces of string on the sides are spinning like crazy, which would seem to indicate that most of the turbulence we get with this screen comes from air spilling around the sides. The ones on top don't seem to get much disturbed air at all - hanging down in the first two cases (no cutout and small cutout) and blowing straight up with the big cutout.

Too early to tell if the big cutout is going to ease the turbulence, but I suspect even if it does, there will still be some from the spill around the sides. At least this tells me that if I DO get a replacement screen, I should be looking for a wider one, not necessarily taller.

Testing a screen cut-out on the Super Tenere