This is not urban legend. It was JOKE by lead designer. He said (smiling) "we cut Jazz motor in two".
It is amazing - interview was published, mentione "he smiled and said" and nobody got it - hence urban legend created by readers and not engineer.
But this motor has nothing to do with motorcycle engine indeed. It is scooter motor. Nothing against maxiscooters, just clarifying. It was first meant for maxiscooter platform and NC derived from it. Cost-wise smart move by Honda indeed.