First, any performance "issue" is initially addressed with a complete and thorough tune up check list completion.
For an unknown motor, it is nice to have a compression or leak down test to ensure mechanical health.
Then, the CB550 should do a 1/4 mile standing start in the low 14s. ( 8.66 sec 1/8mile, 14.02 sec 1/4 mile from magazine tests with a 150 lb rider of the era). That's a real performance metric that doesn't rely on your butt to make a judgement call.
If your bike has been modified to ruin performance, then either take it back to stock, or keep fiddling with it to try a restore the owner mistakes you've inherited.
While the F model had a 4 into 1 from factory, it also had a high pressure muffler (quiet), with the stock air induction, this required a smaller main (98) and a different profile slide needle. Neither is suitable for pods of any brand or design, or an aftermarket muffler.
Pods of all designs change the carb throat pressure and therefore fuel draw from any jet placed in it, stock included. That is why pods generally require larger fuel orifices (slide needle and main). An open loud exhaust, also requires a bit larger orifice size, as less unburnt fuel is retained for the next firing cycle. Engines don't breathe with 100% efficiency.
The fastest way to achieve proper carb tune is with dyno and exhaust sniffer.
Alternately, learning to read plugs and a test track can be used to get proper mixtures. A "plug chop" can be used to determine what your engine needs, given the design changes to exhaust and induction. I set main size first to set maximum demands of fuel for the engine. engine at operating temp, install new or clean as new plugs. Start immediately do a full power WOT run to top speed. Swithc off ignition and pull in clutch, brake to a stop. Pull out the spark plugs and "read" the spark plug deposits. Dark/ black = too rich, White insulator, melted electrodes = too lean. Adjust main jet size to the test produces a light tan deposit pattern on the center electrode insulator.
Now mark your throttle to determine where 1/2 throttle is exactly. Repeat the "plug chop" procedure but, using only 1/2 throttle only. Run this way, (uphill is best as you want max load on the engine during this test), and again "read" the plugs. Raise or lower the slide needle to again achieve the light tan insulator pattern ( you need to start with clean as new plugs for each test).
Next test is for 3/4 throttle. If you plug reads don't come in tan, then the needle taper is wrong. You have to change the needle profile to correct this if too rich or lean. If you have F needles, you can try using K model needles. Do the 1/2 throttle testing first, to set needle height, then do the 3/4 throttle test. to find out if mixture is correct for that position, too.
A 1/4 throttle test will determine, if the needle taper is still good for that position. This is harder to do as the power and heat for deposit reading are marginal.
Lastly, the pilot screws can be set for correct throttle response. Rolling along slowly, in top gear, snap the throttle to 1/2 position. Correct response is a slow but steady acceleration. If you can do more than 1/2 throttle snap, the pilot mixture is too rich. If the engine wheezes and falls flat until you reduce throttle, the pilot mixture is too lean.
All this gets dialed much faster with a dyno and exhaust sniff. But, that cost more money.
Of course, this is all easily avoided, with restoration to stock, as Honda engineers, did all that proper mixture adjustment for you.
It's your call on the path you take. I'll mention a third alternative, and that is to make random carb adjustments in the hope you'll stumble onto an aceptable running compromise, before you quit from frustration or sell off the problem to someone else.
It sure is a fun bike when it runs well, though. But remember, the little engine makes HP above 4-5K RPM. Low torque below that. It's happy to wind up to redline for it's entire life. Use the trans to keep it in higher RPM for snappy throttle response. A good rider can keep up with 750 drivers, most of the time, if your left leg doesn't cramp up from the shifting.
Lastly, the original quiet muffler, allowed using the higher RPM routinely without drawing enforcement officers, attention. It also allowed diving the bike longer distances without sound fatigue for the rider. But, good luck finding an original muffler in good condition after all these years. I can add that the stock set up F model can achieve 50 MPG. Never heard of 550 modified with exhaust and pod changes to do that! Even if you don't care about MPG, you have to admire the efficiency of a well tuned set up.
Cheers,
