It depends how far from stock you want to stray. Any nonstructural part of the bike that was originally steel could be fashioned from aluminum or even titanium. The aluminum D.I.D. wheels from the 750A model come to mind first, JT Sprockets has aluminum sprockets available, most modern bikes use hollow axles, rearsets are always lighter than stock controls, lighter handlebars are certainly out there, some of the headlight setups that use H-4 bulbs are plastic as opposed to the heavy sealed beams, Smaller batteries or gel batteries, modern handlebar switch pods are often plastic, aluminum swingarms are out there, 520 chain conversions will lose a few lbs, thin walled aluminum oiltanks, 4:1 headers as opposed to 4:4 pipes saves a ton, mini-turn signals will save some weight, ditch the fork ears and find aluminum headlight bolts, plastic or fiberglass fenders, leave the toolkit at home, ditch the starter motor, get a lighter aluminum kickstart lever, cut off the passenger peg mounts, go with a plastic chainguard if you have the steel one, aluminum spacers for the rear wheel, a lighter brake pedal, there's more but I can't think of any right now.
One would think you could drop lots of weight just by replacing one part with a lighter part, then there are parts that can be removed, then there are lots of guys who'll drill everything full of holes to reduce weight even further.
I wonder how much weight you actually could drop? 15-20 percent?
