Forget the sandpaper and Tripoli. It takes waaaaay too long. Take the bar off the bike, and use Mothers' Billet Polish. NOT regular Mothers' (that won't do anything). This stuff comes in a little tiny 4oz jar, and it's like $13 for each jar, but MAN does it work! You can use it to shine all of the alloy parts to mirror finish. Use a 2" buffing wheel in a drill, and have plenty of clean terry towels. Smear the polish generously on the part, and use the buffing wheel to break up all the clearcoat and oxide. The wheel will quickly turn black. This is good! Don't try to clean the wheel. Keep adding polish as necessary to keep the black residue wet - don't let it dry on the part. Once you have broken through to the metal, use the terry towels to buff it to a mirror shine. This will shine all of the alloy parts - grab bar, handlebars, lower fork legs, side covers, rear peg mounts, and all of the engine/gear covers. It WON'T work on the chrome parts, so don't even waste your time trying.
You CAN do this with just elbow grease, you don't NEED the buffing wheel. In fact, I did the grab rail, side covers, and peg mounts by hand in about 3 hours. The engine, handlebars and fork legs proved tedious without the help of power, but it could be done.
And in case you're wondering, the text around the cap reads: "Look no further! This product is unconditionally guaranteed to be the best metal polish you have ever used on billet, forged, and finely cast aluminum, brass, gold, and any other polishable metal!" They are NOT kidding!