Hi. I noticed whilst i was working on the bike that the fairing bolt which holds both side panels together under the head light is missing. Any one happen to know the size and gauge of the Allen bolt in question? Bike is an '88 K75S.
Ta!

Check here;
http://www.realoem.com/bmw/showparts.do?model=0563&mospid=51744&btnr=46_0154&hg=46&fg=63&lang=en

If you put your VINnumber in "Serial number" , you will find exact your bike

It's M5x20. It's actually a cross-head screw and there should be a plastic collar through which it passes into an M5 spring clip.

Numbers 17, 18 & 19 here:

Or in my case a cable tie!!!

I just ordered the same pieces yesterday from the dealer.  Not all thaaaat expensive.  You could probably get second hand ones from Motorworks if you are on a budget.