670 cc: "I assumed the 400X is just a displacement reduced 500X made to align with rider licensing classifications in those countries where it is marketed. I think Japan jumps to a different license class at 400cc, so I saw specs that say the 400X is 399cc...."
Yes, anything at 400 and larger is the biggest class of licenses in Japan and the most difficult to obtain. Although we never saw any of that here, the domestic market Honda motorcycles had all sorts of trick stuff in their 250 (249) and 400 (399) offerings. I remember they even had a 50 cc, 2-stroke scooter with a foot-operated, exhaust port valve!
Yes, anything at 400 and larger is the biggest class of licenses in Japan and the most difficult to obtain. Although we never saw any of that here, the domestic market Honda motorcycles had all sorts of trick stuff in their 250 (249) and 400 (399) offerings. I remember they even had a 50 cc, 2-stroke scooter with a foot-operated, exhaust port valve!