Back in early 1996 DIRT RIDER magazine sent an editor to Japan where he bought a Honda CR250, disassembled it in his hotel room then brought it on board in his luggage and a carryon. He said the hardest part was the expansion chamber; it was big and weird shaped but seemed to fit OK in a hanging suit bag.
They did this so they could scoop the dirt bike world with the first test of the aluminum framed CR, the Japanese market got them in 1996 but US production bikes were not due in the States till 1997. IIRC Honda got PISSED about that whole thing.