Just use a door opener remote made for that opener if you want decent range. The Harley system is old technology that never worked very well, and it should have been scrapped at least a decade ago. They could replace their system with a simple programmable transmitter that works directly with your garage door opener if they were serious about making this a useful option. The fact they haven't done so tells me they don't consider it important.
Btw, I have an older (2010) CUV that came with Home Link, which is similar to what I mentioned Harley could do if they wanted to. It worked great with the old door opener I had when I bought the CUV. When I bought a later and more modern garage door opener, the older version of Home Link would not communicate directly with the new opener. A workaround was provided that involved a separate receiver that had to be mounted in the garage (much like the Harley receiver) which would accept the signal from the Home Link in the CUV, and then that receiver transmitted a compatible signal to the new garage door opener. Guess what, the range for that system was about half of what it was before I installed the newer garage door opener. Adding that extra receiver made the Home Link system in the CUV just as short ranged as the system in my CVO. Find a way to transmit directly to your garage door opener if you want decent range. There may be modules you can buy to modernize the system in your bike, do some internet searches.
Jerry