Edit: After I did this job a couple other TR members gave it a go. Zoomie888 put a few more pics and his $0.02 in a post on page 2. You might want to check it out after reading through this section.
Got the brakes installed today. I've changed brakes on cars before, but never on a motorcycle or scooter, so this was all new to me and it still took less than ~40 mins. I snapped a bunch of pictures and I'll provide some explanation for each one since the Yamaha shop manual's instructions are fairly terse and at times a bit murky.Tools you'll need:
A flashlight is handy if your workspace is at all like mine, although not necessary. You'll need a 10mm and 12mm socket, and having two ratchets makes life a lot easier, so you don't have to keep swapping the socket back and forth. New pads (the ones pictured are my old ones as I took this shot after the install) and a couple of extensions to help you clear the fender when loosening bolts etc. The screwdriver is helpful for positioning the new pads in the springs once you're ready to reinstall.The Lay of the Land
Here's what you're up against. Three 12mm bolts and a (potentially optional?) 10mm up top. The caliper itself (the gold piece) is simply loosened and moved out of the way, but we'll talk more about that later. To replace the brakes you DO NOT need to disconnect any brake lines! I repeat, DO NOT DISCONNECT OR LOOSEN ANY BRAKE LINES. If any brake line is disconnected, the entire brake system needs to be flushed and bled, and that is more work than is necessary. So don't go pulling all the hoses off the caliper all willy nilly.Remove the Caliper Bolt
Grab a 12mm socket and ratchet to remove this bolt. I sat to do this and put my right leg in front of the tire so the bike wouldn't try to roll away. It didn't take too much force to loosen it, so you aren't likely to knock the bike over, but one should be careful so it doesn't roll away from you. Once this bolt is loose you'll be able to swing the caliper backwards (toward the rear of the bike) and see the pads underneath.
I didn't get a good shot of removing the cable guide bolt, but now's a good time to do it. There is a small L-shaped metal bracket held on by a 10mm bolt that fastens the brake cable to the fork as it heads up from the caliper. You might not have to remove this bolt but I found that it allowed me to swing the caliper out of the way of the disc and forks a lot better once I had the Fork Bolts removed. Take care not to lose the small bracket, as it may fall when it becomes loose and if you're not careful you could lose it.Remove the Fork Bolts
These two shiny bolts hold the caliper and the bracket that holds the pads to the forks. You'll want to remove them using a 12mm socket and ratchet. Once these are out, you can swing the caliper free of the rotor towards the back of the scooter and remove the bracket that holds the pads (I'm sure this bracket has a name, but I'm not sure what it is). Once the caliper is out of the way, the bracket will be entirely loose and you can move it to a more convenient location to work.Free at Last
Here's that bracket I keep talking about. This thing has two little metal 'springs' that hold the pads in place. Don't lose them or break them. My replacement pads did not include new springs, and I'm guessing yours won't either, so you'll need these. I do recommend removing the springs and cleaning them and the bracket up as much as possible.Install the new pads
Using the tension provided by the springs/clips you'll be able to position your new pads inside the bracket. Go ahead and do that. Ensure that they are in there evenly, (so that there is equal space between the two pads from top to bottom where the disc will eventually go).Don't Forget the Grease!
Don't forget to put a little brake grease on the pads. You want this to be a thin layer on the pads wherever the caliper will contact the pad. This is very important to ensure your new brakes don't squeak. Even brand new pads can squeak if this step is skipped. I got this pouch for $0.79 at my local O'Reilly's Auto Parts.Greased
It doesn't take much, just a thin layer. Take care not to get any on the disc or the inside of the pad, or it'll burn and smell.Compress the Caliper
Take a look at your Brake fluid level. If you've got a bit of headroom go ahead and compress the brake caliper using a pair of channel locks, until the piston is flush against the caliper. As brake pads wear, they get thinner and the piston will protrude more and more to compensate. Your new pads will need this additional clearance in order to fit inside the caliper and around the disc.Re-install the Bracket, caliper etc
Insert the bracket with the brake pads into the caliper and slide the whole contraption onto the disc brake. It took me 2 or 3 tries to get this to work, but it wasn't too bad once I had my brake pads positioned wide enough that they could fit around the rotor.
Once slipped into position, install the fork bolts and the caliper bolt. Fit the brake line back into the guide and reinstall the bracket and bolt that hold it into place. Ensure the bolts are snug enough and you're done. The first couple of times you pull in your front brake lever, it may compress completely with little resistance, but after 2 or 3 pulls it should resist normally. If it doesn't you may have developed a brake line hole or leak and you'll want to inspect the brake line for such. If you were careful this shouldn't be a problem.
I hope this tutorial helps someone in the future. Let me know if I can improve it in any way or if you have any questions. Thanks.