I still remember watching one of the first Episodes of Then Came Bronson.
He had a Harley Sportster and decided to enter a Hill Climb contest.
Funny thing happened during the Hill Climb, his Harley turned into a Two Stroke Dirt Bike. Forget which brand, could have been a Husky.
I did see Evel Kineval jump a bunch of Cars at Ascot Raceway using a Harley though.
I used to catch at hill climbs in Iowa as several of my uncles and cousins were motorcycle people, one even owned a KTM and Ducati dealership.