My Windjammer 4 was cut like that to mount it on a 6 Cylinder Kawasaki Z1300 Touring Bike. It was done under contract by Vetter as requested by Kawasaki and the data plate on my Windjammer has Kawasaki on it instead of Vetter. It was cut like that to clear the gigantic radiator they used on that bike. I took that Windjammer 4 fairing off that bike along with the bags and trunk from a Z1300T motorcycle sitting in a junk yard. All that stuff is now on my Honda VLX VT600CD motorcycle. The bikes odometer had just 23 miles showing and suffered a crash where it ended up in that junk yard. Apparently the owner purchased more motorcycle than he could handle. Also reviews say that motorcycle wallowded around through curves and was hard to handle in all other riding conditions.
There were two brackets that attached to the bottom of the fairing, a left and a right side. Both bolted to brackets welded on the bikes down tube frames. Just a single 1/4-20 bolt, nut, and steel and rubber washers held them to the fairing bracket on each side. There was a second set of brackets that attached to the head tube with a cross brace with 1/4-20 bolts, nuts, and steel and rubber washers going through the fairing in what was the open space where room was made for motorcycles with headlight shells that were not removable from the triple tree. If you look at that area of the fairing you will most likely find two holes already drilled for that bracket assembly. I used a couple of clamps to attach part of the bracket assembly to the head tube of my motorcycle and also reused it on my Bike. I did attempt to simply drill a couple of extra mounting holes in the lower fairing mount surfaces and use just the lower bracket for mounting but the cut parts of the fairing made it too weak and caused the fairing to oscillate at speed. That's when I installed the upper "Head tube" mount, which solved the problem. I did attempt to sandwitch that part of the fairing with the bracket and another peace of flat steel to give the fairing support without needing to resort to using the upper bracket assembly but that attempt failed. I'm sure that fairing was made for use on Kawasaki Z1300 motorcycles and never sold which is why it's NOS.