they have their place, i suppose this should technically get bumped over to OT. its winter so who cares.
my brother rode my dad's on 'JTT' a few years ago, wasn't at the front of the pack but did a 200 mile + weekend with a bunch of kitted mopeds and held its own no problem. You also gotta remember that old guys that ride them don't push them as hard as they can. My dad granny shifts it and only goes like 30 because he thinks the RPM's are too high at anything over 30 mph. I pretty much redline it in every single gear. Its bone stock and does just about 40, its not making much torque at those high rpms because its outside of the power band, so it will speed up a lot down hills and slow down to 35 going up a big grade, but you can climb just about anything and never dip below 35.
I had a '72 c70 a few years back that i put a pitbike carb, drilled exhaust, hopped it up a little bit, that thing went an honest 45 top speed and could climb hills doing it because it was making so much more top end torque. Someday i'd like to do a mild performance build and mill the head, cam it, big carb, obnoxious pipe... see where you could get. Most hondas from the era respond really well to 'phase 1' tweaks and derestrictions but after that they kinda plateau. When we raced the CB160/175's you could get quite a bit out of them by milling the head, retarding the cam, going to PE22 carbs, and piping them... but after that they didn't get much if any faster until you started getting crazy with big bore kits and reworked valves and stuff... the semi-hemi combustion chamber in them burns so slow that the typical cam work doesn't yield much, and Soichiro and team already had them producing pretty good power for the displacement.