How do I clean/polish the aluminum on the engine and the rest of the drivetrain? I am doing a rebuild of my 1985 K100RS and there is quite a bit of oxidation and other dirt/grime. Are copper brushes OK to use? Will they take off any protective coating? What do I use to polish?

Hi.
Be careful using wire brushes. I used a small steel rotary brush in a drill on the differential but the finish came out too shiny. Now I'm stuck with it.
Have a look at these - Garryflex Blocks.
Possibly something similar is available in the US.

Comberjohn

you could take it and have it bead blasted to get the matte finish again, couldn't you? I think its just dependent on the type of sand they use. cheers B

Bead blasting would be the ideal solution and if I ever do a rebuild I may do that. In the meantime its not bothering me so much that I would take it of the road right now!
I believe there is a difference between sand and bead blasting. One obviously uses sand and the other uses small glass beads.
Sandblasting is good for removing rust or paint from metals but leaves a very matt finish on aluminium which quickly absorbs dirt and oil stains.
Bead blasting 'seals' the surface and would be more suitable for bike parts.

How about a really radical look by taking the shiny polished look and using the cork in the electric drill with abrasive underneath to give the circular swirl marks where all the swirl O shapes touch each other, then varnish it to preserve it under clear varnish. Usually the next row are offset so the O's nest into each other rather than being one above the other like they show below.

OOOOO
OOOOOO
OOOOOO

Regards,
K-Bike

I know this process, this is commonly used in gunsmithing and is really not easy to do especially on small parts.
They key is to use a press mounted drill and secure the piece to be finsihed and move the piece with steady movments.
The cork must also be shaped as a point.
Medium abrasive valve breack-in paste works well for the purpose.

Personnaly, for cleaning the aluminium, I'm using "steel wool" 000, like the one used in cabinetmaking, this works well for the engine and wheels and it's terrific on chrome.

Again, this is for cleaning purpose only, some oxidation spots will remain... All the charm of a 25 years old bike.

Rgds

I'me using a dremel with a home made "scotch bright" brush on it.
Works perfect and allmost every spot is accessible.
Do use a breathing mask/filter. It's a dusty job.
Goodluck
Bart

I used "Scotch brite" too, but the idea of making a small pad for the Dremel tool is a great idea.