Beadblasting 102
I was so chuffed about my fork stanchion (see Yamaha RD 350 LC 31K section), That I decided to give my crankcase covers a go. Add to that funds are getting pretty low and you have all the excuses for doing the jobs yourself.
After inspection, I noticed that the original covers I could compare with were clear coated and had ton of scratches behind the clear coat. Not that surprising if you consider these bikes were built on an assembly line: Polishing alloys to a mirror finish takes a wad of time. So I suspect they were polished to a half shine and then clear coated, the coat gives the shinyness.
If you look at the rear fender, you will also notice traces of cost- andd time-cutting: the chrome is only polished on the visible portion, the one that sticks out. Underneath the seat, the fender is real scratchy as in using a disc grinder to make passable before chroming.
So on to the covers: This is the original clear coated (and slightly yellowing) chaincase cover, complete with corrosion and crows’feet.
And that’s after hitting hit with the bead blaster, always low ressure (2 bar) and medium sized glass beads.
The surface is now cleaned, but I didn’t remove the few marks that were underneath the crow’s feet. To do that you’d have to attack it with sandpaper and reblast it afterwards. The result is a very even surface.
After that I just take the stell wool pads with soap and give it a rough wash/polish under running water: this removes all the dust and starts the polishing process. It also removes whatever grease is left.
This is notably smoother and ready to be hit with finishing polish, the type that comes in a can, a paste. I use something called “Alu-Magic” but ost other stuff should work. I prefer to advance in small steps as all I want is to get a even COLOR to the cases. I’ writing that a few days after the job and already can’t rember what I did! I think I just took the steewool pads and the polish and did it by hand… or did I hit with the bench machine? Anyway, very pleased with the end result:
