The reason all Hondas were originally red is pretty simple. In September of 1945, when Japan tied (with Germany) for 2nd place in WWII, the country was devastated. Everything was in short supply.
Soichiro Honda started making motorbikes in 1946 with 2-stroke motors that ran on turpentine, (since there was no gasoline) and were all painted red. About the only thing that there was a surplus of, was red paint. Rumor was that Japan had stockpiled tons of it, to be used to paint the “Rising Sun” logos all over their half of the world after they won, and divided it up with the other Axis nations.
So that’s why red is their showcase color. They probably still have some left. You guys with red ones may have 75 year old paint on your machine.
Honda Motor Company is incorporated