Its not that some people have trouble tuning the carb(s) after putting on pods - its that everyone who puts on pods has tuning problems. If you want carb problems with a 550, put on pods, its guaranteed. Now, as to the jets, you can get whatever you need at Jets R Us. But you should be prepared, all 550's didn't use the same carbs, in fact they changed carbs just about every year. Look on the sides of your carb bodys and see what is stamped into them. An example of what you'll find is for '77 bikes they will be PD46A carbs, but in '78 they were PD46C carbs. Some screw in, some are push in, depends on the carb model.
On my 550K engine I've got the air intake that TinTop in Toronto, Canada is making. I believe he's made about a dozen of them for 550s and a few more for 750's. He sold out the first batch but I believe he is making up a second order. You could do a lot worse than to just buy a set of them and have both a better looking setup but one that actually improved the performance, not one that made it impossible to tune. But back to the carbs, I'm using 110 Main jets, 40 slow jets, and the needle raised 1 notch. My carbs are PD46As and so what might be thought to be air bleed screws are actually fuel enrichment valves (pull on and take a look at the end of the needle, if its tapered its adjustable, if its has square notches its just an On/Off valve). So the are set at the factory recommendation of 1.5 turns out from seated. Opening them any more or closing them up to a half turn wouldn't make any difference at all.
By the way, the problem with pods is that they create turbulent air right at the carb throat. They don't have anything at all like a velocity stack preceding the intake, which is necessary with these carbs to straighten out the airflow going in. The reason they don't have any such thing (even the good pods by K&N) is there is no room for them in a pod's design and without it TinTop has designed a set of internal velocity stacks that hole an aluminum plate that retains a cleanable filter. Its a super slick setup and reasonably priced.
