When you extract the float swivel pins, do it gently and do not pinch them. Polish these pins and also the conical tip of the float needles and their seats. It really doesn't take much to have them clean. WD-40 or a little carbcleaner is fine. Be sure not to use anything that can abrase. I myself would not dare to use steel wool. You can cut a measure tool out of an used credit card and check the float height as shown in the Honda Shop manual. Provided nobody messed with them, it is almost certain the floats WON'T need adjustment.
OK, you are almost an expert by now. You could pull the main jets (very easy) and have a look at the little O-rings around them. They must seal well. Now to have a close look at the needle jets (aka emusion tubes), you could raise the gas slides, imitating full throttle so to speak. In my experience the tubes will drop by gravity. If not, you can help them a hand by inserting a wooden pick from below, cant it and wiggle them out. A little WD-40 at forehand can help. You want to keep them in the order they were in: 1, 2, 3 and 4. Check the tiny holes in the sides. They should be open. For the inside of the tubes you could use a pipe cleaner with some carbcleaner. Again, abstain from anything abbrasive. Leave the needles where they are. You may spray some carbcleaner up there, but that's it. Push the tubes in again followed by the main jets. By now, you have completed almost everything you can do. I do not know if you have removed the float valve seats. If you did, it wouldn't harm to blow air in the opposite direction of the fuel flow. Make sure you put in the float valve seats in the right way. Check again the floats can move easily. On assembly, make sure the floats are in the center and will not be hindered. Screw in the slow jets. I do not know if you have removed the airscrews in the sides of the carbs. If you do, first turn them in (gently!) to determine the position they were in and keep note of it. You can now screw them out (do not loose the little springs) and spray carbcleaner in the holes. Verify the airscrew are clean and undamaged. Screw them in again in the position they were in before you removed them. Done.
You can now fit the floatbowls again. You can reuse the 16 screw heads ofcourse, but I choose to replace them by allen screws (see pic). Note that you did NOT have to remove the toplids. No need for it. There's nothing to clean in there.
What I have learned from experience, is that the CB500 and early models CB550 are very sensitive to have the correct fuel lines. If you have the standard petcock, length should be 18 and 30 cm resp. with an ideal internal ⌀ of 5,5 mm. Outside ⌀ will be around 10 mm. Route the fuellines correctly using for fuelline to carb 3 + 4 the little clamp you will find in the front of the carbs. Make sure this particular fuelline will not have an 'up and down' if you know what I mean, but will facilitate gravity to do its work unhindered. No extra inline fuelfilters. They'll bring trouble on these models.
