The trouble with custom motorcycles is that, more often than not, they’re one-off products. By the time most of us lay our eyes on them, they’re usually spoken for and rarely built more than once.

Early in my motorcycling days (mid-2010s), I considered myself such a motorcycling “purist” that I thought anyone who happened to have, say, a windshield or full-face helmet wasn’t really riding. Fast ...