There's just something powerful about flashing your high beams as you ride up to your home and watching the garage door rise on command, especially on a cold miserable night! And, it's a pretty simple and inexpensive DIY project - I've done it for each of the motorcycles I have owned.
Here are the steps...
Step 1
Start with a garage opener remote. It's important that 1) it's both compatible with your garage opener and 2) it uses a 12v battery (such as the A23, 23A, or 27A). My garage uses a Genie opener, and in this case I just took apart one of the Genie remotes we already had. You will want to pair the opener and remote before doing this modification, making sure it works as it should.
We're about to frankenstein this perfectly good garage remote...
Step 2
Pop open the remote. Easy.
Step 3
Desolder the pushbutton switches. Solder a jumper wire in place of the main switch, bridging the contacts where the switch legs came into the PCB board. This creates the effect of the main switch being pressed continuously.
Desolder the battery contacts and replace them with some long power leads. Be sure to use color coded wire, and double check that you have the polarity the same as the original battery. (I blew one opener because I accidentally switched polarity on installation - oops!)
Step 4
Test by applying the original battery against your new leads. The garage door should open when power is applied.
Step 5
Wrap it all up in a ziplock bag and seal with electrical tape. All told, it only takes about ten minutes to get to this point.
Weather sealed for winter riding!
Step 6
On your motorcycle find a good cubby to hold the bagged circuit board. Check for space under your seat, or in a hollow fairing. On my Honda NC700X I found some empty space next to the ECU.
Step 7
Find the wire running from the high beam switch to your headlight - tap the positive lead from your garage opener remote into this wire. (On my Honda NC700X I found that Honda had carried a high beam wire to an auxiliary harness near the ECU, so wiring was a cinch! For detailed instructions on wiring the NC700X see my post on the NC700 forum.)
Step 8
Connect your remote's ground lead to the motorcycle chassis.
Step 9
Turn on the ignition and test the opener by flashing your brights!
Note
One remote I converted would fire the code only once when power was applied, so no worries about driving down the road constantly pinging your code out to the neighborhood when your high beams are on. I believe most modern remotes work this way. But, another remote I converted fires the code continuously when activated. This can be annoying, as flashing the high beams a bit too slowly will result in the garage door stopping, then reversing. With a little practice I got the timing right, but you might want to test the remote before you take it apart and save yourself the grief - when you press and hold the main button check that the garage door only responds once and doesn't keep going up and down as you hold it.