OK, it sounds like the condensors are at least not bad? The bad ones break down in 1-50 miles, acting just like you've described when they do. REALLY annoying... I don't have any experience [yet] with the Common Motor condensors, so I can't say whether they are good, bad, or ugly, but if they don't cause misfire they are way ahead of the Daiichi versions.
Here's what's key to understanding the sometimes-tense relationship between the too-soft spark advancer springs and modern gasolines: these engines were set up with the quickest-practical (in Honda's eyes) spark advance for use with 1970s premium grade fuels so as to stop the "sudden on-off throttle" action that the 750 is/was famous for having. The long intake runners from the carbs allow a gentler slowdown when the throttle is closed, while the [too] soft spark advancer springs hang "out there" a bit longer to help burn off the residual fuel of the long intake runners and slow-burning premium gas. This also made the engine run cooler (but the exhaust hotter, hence their short lives) so Honda had to use the hotter D7E sparkplugs to burn stuff away.
Enter EPA and its manipulations of our gasolines (and skipping over the 50 years of BS this has caused...) and today our regular grade gas burns even slower than 1970s premium did, so as to help light off catalytic convertors in cars, among other things. For cars, this takes a full-blown computer to track temperature vs. spark advance. All we have to work with is: springs. So, what to do (and 'why')?
Slowing down the spark advancer's advance rate while making it return to idle (5 degrees) quicker to help reduce the 'smoothing' that Honda did with the old gas will help return the engine response toward normal now. Trouble is, it's a laborious process: good part is: it only has to be done one time to make the 500/550 long intake runners stop making the engine so slow to respond.
I do it by trimming back the advancer springs. This process will be going into the next book, too, because it is needed for the 500, 550, 350F and even the 400F engines (and probably the 250F, but I don't get to work on those very often and haven't tried it there). The mighty 750 suffers from it, too, although not quite as much because its intake runner length is half that of these smaller bikes.
To start: notice how loose the advancer cam is at idle: it almost can't return to idle when you twist it by hand and let it go. I cut off one full turn from one of the springs as a starting point: you could also cut 1/2 turn off each one for the same result. It will help it return to the "F" marks more easily, but it likely won't stop all the after-running that is being caused by the long intake runners. On very low-mileage bikes, this is [barely] enough to settle them down: in the 550K3/F2 or higher-mileage [earlier] 500/550 engines, not so much. These later bikes have Honda's first 'smog-controlled' carbs on them, and they run richer - if more tightly "controlled" [sic] by having a non-removable jet - at idle, leaner during acceleration, and normal above 4500 RPM (due to the way the US DOT wrote the smog-permit laws in the 1970s). This makes these bikes sluggish on acceleration because the engine is spitting back its too-lean, didn't-light-off-yet fuel from the last intake stroke, which then wetted the intake valve's face with unburned fuel, and the next intake stroke got it wet enough to burn, so...it finally fired, and the cycle restarts. Honda could only reduce this by delaying the intake valve's opening (like they did on the 750F2/K7 engines) to 0 degrees, which helped dry the intake valve and reduce this activity, which in turn reduced unburned hydrocarbons...which got the DOT off Honda's back. This info usually DID NOT make it into the Shop Manuals, though: most of them I have seen show no changes to the cam intake specs, but the cams do.
So, after all the mess, what Honda DID NOT do was: spend extra on getting better-tensile springs in the advancers, because they were still trying to make a Yen or two on the bikes. After about 8k miles these springs anneal and start to soften: in the earlier bikes the wetness of the earlier carbs turned this into a smooth coasting action: in the smog-controlled versions the deceleration lean gap between 3500 and 1800 RPM became a trash-collector of
([whatever gas was left]+[the next intake stroke] = no burn this time around)
which will stay rich until the springs retract the spark advance angle enough to slow the burn rate and let the piston speed drop, so it will stop sucking on the carbs.
So, in the 1976/1977 versions of the 550, I always start with 1.5 spring coils cut off: 1 on one side and 0.5 on the other. It usually ends up being more than that before the engine responds and acts normally. On the earlier engines with more mileage, the situation is very similar with the springs, which makes the engine sputter-fire enough during deceleration to make the Hy-Vo primary chain 'wave' a little, which then causes it's slack to hit the upper side of the engine case, making that rattling noise...it's all connected to the spark advancer.
