Recently saw a highly customized R100 at the Centennial BMW Rally in Monterey, CA.
Bike had a nice tight fitting perforated metal plate mounted in front of the soft radiator fins.
My "naked" 1990 K75RT sports an oversized K1100 radiator without any form of shroud. Radiator works well but the fins get dinged by airborne chunks of rock and metal.  Would like to install a protection plate to avoid a puncture.
Any suggestions or details on how you did a similar modification most welcome.
Thanks!

I wonder how much those screens cut airflow...compared to the type of screening that is stock.

Living in the humid South I may be paranoid...

I agree Brad-Man. My feeling is that 'expanded' mesh, as used in the oem grill will allow far greater air flow than would 'perforated' mesh or even woven mesh.

Here's a simple solutuon using the original expanded mesh grill.

the airflow restriction is equal to the percentage of surface area obscured by material .

It's 48% open on the big stuff.  No issues on my K100. To get more detailed we could go into the turbulence it adds to the airflow and how that impacts cooling at various speeds but since it works I don't care about that.

I forget the percent for red K75S with the smaller stuff but that bike didn't have issues either. 

If you think about it, you don't really have to be going that fast for airflow to work on the radiator so, at least to me, it's not a big concern.

On my K75 with a K1100RS fairing I used expanded mesh just to try something different but next time I'll probably go back to the perforated stuff since I think it looks nicer and it's easier to keep clean. (Yes, there's a bare radiator behind it but my phone blurred out the fins when it focused on the foreground.)

I think Washington state may be a little cooler than temps we get here in AU Duck. Summer before last we experienced temps well into the 40s. Also if you are commuting, air flow becomes important when the fan is kicking in every ten minutes or so.

Here's a little bit of info about expanded mesh I found this on a suppliers website.
Most of these expanded meshs have about 60 to 70 % free air space when angled.

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Here's the URL.

Free Air Space

Free air space is the percentage of the viewable expanded sheet area that is space, as opposed to metal material.  Approximate values are provided in the product selection chart. Values for raised expanded metal vary from lowest value at normal incidence (i.e. when viewed with the sheet held at right angles to the line of vision) to highest value at maximum incidence (i.e. when viewed with the sheet slanting so that the strand width is parallel to the line of vision, thus presenting a greater free area).

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Thanks for the backup Holister.

I had the down under contingent in the back of my mind when posting because ya'll have as bad or worse conditions than I do in the Deep South where I ride.

Seeing that after my parents pass I will probably be moving to around Austin, TX or slightly west of there to be near grand kids I am concerned about this.

My '85K100 currently has no protection.

I have the original Shroud and side panels for a naked K100 but don't know if I want to use them.

I'm gonna have to say that form is gonna have to follow function here - pretty be damned.

I dated a LOT of pretty girls before my 1st marriage and between that one and my 2nd.

The one I married last 25 years ago wasn't the prettiest, but she's damn close to it and a hell of a lot easier to live with....

Just sayin'.

Hi Knave, you might be interested in how I mounted my stone guard on the radiator of my naked K75 during my customisation.

Have a look halfway down the first page of my build thread for a couple of photos and description.

K75Xcountry build thread

Cheers

Here's my suggestion: http://www.snapdeal.com/product/chrome-black-mesh-dustbin/629744509

Several replies zeroed in on exactly what I am trying to do:  install a stone guard in front of a naked K75 radiator.  (I have an oversized radiator, possibly from a K1100, and a K75 radiator shroud won't even fit over it.)
I am thinking heavy duty mesh at this point, rather than perforated plate, due to airflow factors well covered in the replies to my post.
In addition, attaching mesh to the radiator frame requires less machine work than attaching a perforated SS plate, judging by several of the detailed responses to my original post.

Installed a custom welded SS stone guard in front of the oversized naked radiator.
Very happy to get a more finished look, since stock radiator shroud won't even fit over this radiator.
Bike is a naked '90 K75RT.