Here's what it looks like installed, with the weather-proof cap flipped open:
As I discovered from a lot of Googling, there are many crappy USB adaptors on the market. Save yourself the hassle and order a 3BR Powersports model. It's overpriced for what it is, but the materials and quality are top-notch (if a little rough-looking). I got mine from Motorcycle Innovations--it's the 2.1 Amp model (not the "lite" version) which provides plenty of juice for more demanding loads like an iPad.
Here's what's in the kit:
There's a trick to accessing the nut under the triple clamp to remove and install the bottom bar clamp. You can't easily fit a 17mm socket in there unless you rig a universal joint like so:
The left side is then easy to access and wind off. However, the right nut is further defended by a little ridge in the head tube. To get the socket on, you have to crank the bar full right, slip the socket onto the nut, then move the bars back. This holds the socket in place on the little ridge and then you can crank it off.
Installing the bottom clamps is the reverse operation. The bar offset should be to the front (moves the bars forward).
To keep the clamps from spinning when you tighten the nuts, it helps to first install the bars. See the little dimple above the top bolt holes on the top clamps? Those should face forward. Install the front bolts first and wind them all the way down. Then install the rear bolts and tighten them by hand just enough to keep the clamps from spinning. Don't worry about bar location for now; you'll adjust that later.
Now tighten the bottom clamp nuts to 40 Nm. Then loosen the bar clamp bolts, adjust your bars, and tighten the clamp bolts to 28 Nm. Official instructions here in case you don't believe me:
That's it for the handlebars; now back to the USB.
The 3BR wiring harness includes a moulded-in fuse holder and rings clamps. I cut those off so I could wire directly into my switched distribution plug from Eastern Beaver. I didn't have a free plug slot, so I ended up paralleling my GPS wiring with the USB, and sharing a fuse. Note that the 3BR comes with a 7.5A fuse which is way too high for a 5V, 2.1A USB plug. The plug can only deliver 10.5W, which draws less than 1A at 12V on the feed wiring. I installed a 2A fuse which should be fine for running both my GPS and USB together, and yet protect my wiring if the plugs ever do short out (e.g. from swimming).
Wires were both crimped and soldered into the spade lugs before covering with heat-shrink tubing:
The Eastern Beaver switched buss is shown at the bottom with the red and yellow wires sticking out. The GPS/USB wires run to the right of the airbox vacuum actuator (silver thing) and follow the clutch cable under the gas tank and up the left side of the bike with the rest of the wiring harness. Very easy to thread if you start from the handlebars. A few zip-ties keeps it neat and prevents rubbing that can lead to shorts.
The 3BR isn't waterproof unless there's nothing plugged in and you have the cap on. That's not very helpful, so fortunately they sell this little kit to waterproof your USB cable end. Just slide your plug into the rubber cap, and wrap it with the included silicone tape. It makes for a tight, waterproof seal on your cable, and when you plug it in it'll be pretty much waterproof from rain or heavy splashes.
It even works with those tiny Apple USB connectors. No prizes for my wrapping job. That silicone tape is pretty nifty stuff... going to see about getting more for other applications.
Everything fired up and works great, and with my lower bars I hope to have a better riding position when seated and standing.