my veterinarian has a '68 beech bonanza and a '72 honda ct90. he had a guy saw the down tube in 2 and weld in a hinge so it could fold and go in the luggage door. so well done, it looked factory, paint and all.
like,
totally voided the bike's warranty!
the bike's handlebar had a hand clamp (factory) so the bar could pivot sideways. and the mirrors unscrewed by hand.
l