! This stuff is amazing! It's expensive in quantity but I think you can get a small kit on Amazon that will do what you need for a minimal price. I found out the hard way just any plastic repair stuff won't work on bike plastics--including the FJR. I used it to practically rebuild a busted side panel on my FJR. It has held strong going on 3-4 years..actually stronger than the plastic itself. Also, repaired a stripped plastic screw hole in the nose panel. Really good stuff to have on hand for anything involving plastic repair.
I use Plast-Aid (probably similar to Plastex). It is a two part compound (powder & liquid) that really works well to mend or make plastic parts. I recently used it to repair the plastic tab on the windscreen cover. It worked well and the mended part is stronger than the flimsy OEM tab.