Congrats to you, Mark. I don’t have a 500/550 at the moment but something tells me I’ll still want the book! Cheers, J.
P.S. my ‘78 550K was my first “big” Honda motorcycle. It came after my 1970 Triumph T100S (500 twin, single carb) and I was blown away. The only thing I changed was the bars. My wife wanted higher bars of her 400F, so I swapped them. Both fabulous machines. Always on a Honda since.
Wow, you had a '78!?
I had a '78 550K, it had minor crash damage when I bought it. Made repairs to it and then decided I like the F model better so I sent it down the road. I didnt notice it being any faster than my other 550's and I didnt care for the exhaust on the late models ['77-78]
Yeah, a lot of folks thought they were too "ballooney" in size (a common complaint of the 750K7/8, too), like a caricature or something. While I think Honda was walking the EPA emission tightrope with them, the last version of the 550K was the first one I found to run over 100 MPH. All of the "F" bikes would do it downhill, but on the flat they would reach up to 95-ish, and the last 1/4 throttle made no difference at all. If the float bowls were deepened a little bit (like 1mm more or so) they could touch 100 MPH when lying flat on the tank, but sitting up would drop them right back down. The 4-piper last version has a weak upper midrange (3/4-7/8 throttle range) because of the jetting: using the slide needles from the earlier versions of those PD carbs could fix that, but also ran the HC readings up past most major (USA) metropolitan allowances and could make them load up a little bit, fouling sparkplugs in slow freeway use. But, once past the 7/8 throttle range they perk up again, indicating the lean mix of the upper needle range (don't forget to back out the throttle-stop screw to get there...). Like most emissions-controlled bikes of that era, it takes a tricky (and patient) tuner to get them to run to the ton readily (heck, we were supposed to be going 55 MPH, right?). Many who just bore another 50cc into the engines to get there find that it doesn't stay there very long: as soon as the heat-cycling warps the 2 outer bores again the ton goes away, just like when they were new. 'Tis always better to step-bore these small ones, as the newfound power will stay there.
