I bought a product called Plastic Renew at a local moto shop. It s from PCracingusa.com (I have no ties to them). It s for my 99 s fairing, but I tried two small jobs first. My old pickup has those aftermarket visors on the windows, I think they look like eyebrows, but that s just me. Mine are translucent smoke color. One of them came off and in getting the residue of the old adhesive off I used Citrustrip, which clouded the plastic. The Plastic Renew worked great to clear that up. Then I tried it on a scuffed clear plastic taillight lens on the car: again, worked great.
An 8-oz bottle comes with three grits of sandpaper and instructions, for $21. You wet sand (220, 320, 400), then wipe on the product, wait 3-5 minutes, apply again. Instructions call for four applications. The approximately two square feet of my two projects used about an eighth of the bottle. The supplied sandpaper was more than enough for my two little jobs, but not by much.
I dunno yet about longterm effects, but the immediate effect is great. Next I m going to try the pickup s headlight lenses, which are clouded up after 14 years. Then a small spot on the KLR plastic. But I have more pressing work on the bike, which needs repair after a low-speed crash a few weeks ago.
-James