On the oilhead bikes, there is no bare aluminum on the bike, everything is painted .
When I had my transmission rebuilt 2 years ago, I was asked if I wanted the transmission case glass bead blasted, my comment was, it's taken 27 years to look like this, you don't mess with perfection .
I can understand your wanting to get bike to look presentable again, but using abrasives on bare aluminum will probably wear you out before you're satisfied.
Bare aluminum does what aluminum does best, tarnish, and turn gray .
American Airlines doesn't paint it's aircraft, they polish each aircraft about every 3 weeks, but if they did, they could reduce the manpower in their cleaning department by 50 % .