I would start by reading all the old post here_ https://motorbicycling.com/forums/diy-home-built-motorized-bicycle-non-kit.36/
and here also _https://motorbicycling.com/forums/board-trackers-and-vintage-motorized-bicycles.38/
There are so many hand built, with ton of details, and howto's go back before the corvid hit for most.
and here also _https://motorbicycling.com/forums/board-trackers-and-vintage-motorized-bicycles.38/
There are so many hand built, with ton of details, and howto's go back before the corvid hit for most.