It wouldn’t be as hard as it looks. You could buy a cafe seat from Amazon, work up all of how to adapt it, then make a plug and build it yourself. It would take patience, but it could be done.
I would definitely say custom as a motorcycle seat is considerably wider. It would be much easier to make a new piece than try to rework an existing piece. They did a superb job.
I would say it’s a custom unit. It’s too small to have come from a motorcycle, unless it was reworked. My immediate guess is that someone is a composite bodyworks builder. I could post an “all you have to do is...” sentence, but that would absolutely SPOIL the beauty contained in this photo.
That is how some shoppes operate.
When I was a wrench in the shoppe, essentially I NEVER saw a customer UNLESS I was explaining the work that I had to do or I was specifically being asked about a part for a special situation, as I tended to be that guy. I set up a bike with a two to one cable...
When I was a bit younger and didn’t show my age, I used to love to catch bullshitters! It was great fun. Now my age kinda shows and I can’t look quite as gullible LOL
Fork is installed. The new one BELONGS and actually makes the stance better due to the longer legs. Disc brake front wheel is finished (not picked up). Hopefully my seat guts arrive today or tomorrow. A lot of little milestones today!!!