The inline 4 bikes just run lean in those years, counting the entire later DOHC pack of '84-'86 550, 650 and 700 I can't say I've seen 10 of them total since they were made except when I walked into a showroom. Honda was too busy thinking V-4s around that time. Then most who bought them never put a header on, it ruined the lines of the bike to that type mentality, I don't think I ever saw a headered one in all 3 of those. Thinking very few headers ever got sold or even made to begin with.
The bikes are considered 'custom' and most want the full 4-4 or 4-2 pipeset, a one-sided header spoils the 'look' too much.. Even the bigger C model owners prefer 4 pipes but are forced to go to header later when the owner cannot find the 4 pipeset. More likely to find a header for the plain jane K or F type style of which those 3 never came in.
V-4 models the same, the headers for them were quite expensive due to the needed design and they sounded pretty bad anyway, the V-4 sounded like a straight 4 running bad, like a cylinder not working, a flat dead sound.
