geno.box, armpump gave you the right material link. Available from most hardware stores, Midas etc. There's one that is especially flexible, almost rubbery that I find work better than the general canopy seal strips.
The thread is however a bit outdated guys. The bike was sold shortly after the last post here. If there was a guide on the sprocket guard it would've gone back, if not, it probably still looks like in the photo. No incident to date after many miles with the new owner. He's got the link to this thread so will let him know.
Rivets was SS if memory serves correct Katana.
