Harley engines are 45 degree. (Except for the V-Rod, which has a 60 deg engine)
What makes Harley engines sound so unique compared to other twins is that the crankshafts are single pin. Most twins have staggered crank pins to fire cylinders evenly at 360 degrees apart. On a Harley, they fire at intervals of 315 degrees and 405 degrees.
Obviously Harley could make a staggered pin crank shaft. This is old tech to be sure. But it’s the sound. That’s why Honda started to copy the sound with their VTX1300 engine. They went backwards in tech to copy Harley.
Another Japanese manufacturer has topped producing overhead cams on big cruisers and went to overhead valve and pushrods to similarly copy Harley. Yamaha “Star” cruisers and their successors for example.
Thanks for the correction. I knew HD used a 45° V I just slipped. Aprilla uses a 70°. My Ducati is also a single throw crank, but the rods are side by side, not the HD “knife and fork” setup.