Jason Mamoa has a traveling adventure documentary show, on Max streaming service... and the first episode is about building a 1936 Harley, a bunch of guys focused on the early Harley's, who want to race up hills on really old Harleys.

 So, he met a LOT of hardcore vintage bikers, and vintage bike racers, and Mike (American Pickers) and bought the original stock parts of 1936 Harleys that Mike had collected, and had a 36 built. 

And he bought a Harley DH, and had it scanned into a 3D computer file, so exact replica castings could create three new 36 Harleys, so he and his bike club "The Roamers" can go hill climbing, as men once did on early Harleys. A project that started around two years ago, but just got to Max a couple months ago

Because only 12 original DHs were made, no 4 were ever together, running at the same time, and only a handful of guys have ever ridden one. Until now. 

https://www.imdb.com/title/tt14675396/
https://www.thegearpage.net/board/index.php?threads/on-the-roam-w-jason-momoa.2536440/
https://www.reddit.com/r/HBOMAX/comments/19b47bv/on_the_roam_by_jason_momoa_is_really_inspiring/