I still don't know which carb style the OP has even though I asked about that as well as other things that were ignored.
But, in case someone else reads this and gets a misunderstanding about how the 550 carbs work. I'm going to correct/refine some of the things posted.
If he has a # 40 IDLE jet and just say a #130 main jet. Your idle circuit is where you draw fuel from at IDLE up to about 1/4 throttle then your MAIN jet starts feeding the carbs.
I prefer to use "pilot circuit" for these carbs, as they have no shut off mechanism linked to slide position, or RPM. The circuit forms the "base line" fuel mixture when the slides are at or near closure. As mentioned, mechanical slide carbs that have no accelerator pump do need an over rich pilot mixture to get the RPMs up when the slides are lifted.
I've seen many 750s with a perfect IDLE but when you crank the throttle open it just dumps fuel in and not enough AIR for it to burn = RICH.
I don't see how this is possible without an accelerator pump. When the slides lift, the carb throat vacuum immediately moves toward Outside Atmospheric Pressure (OAP). OAP is what pushes all the fuel through any of the fuel metering jets when and only when the carb throat pressure is less than OAP. Thus, fuel metering volume diminishes when the slides are raised, and less fuel or a leaner mixture is a result. If the pilot mix is over-rich enough to allow RPM increases, the eventual velocity increase causes the venturi effect to lower the throat vacuum and fuel delivery ratios can then be restored.
PODS shorten the entire inlet duct and bring OAP much closer to the carb throat fuel jet delivery points, resulting in less available pressure differential, and less fuel volume drawn through existing jet orifices. To restore the volume of fuel drawn up from the bowl with these lower pressures, the orifice size is increased. For the early carb pilot screws, you can reduce the amount of air introduced to the pilot circuit, which has the effect of mixture enrichment. IDLE Mixture Screws (IMS), found on the PD style carbs, regulate the total volume of the fuel air mix from the pilot circuit. Depending on the pressure drop characteristics of the filter membrane, the pilot air screws or IMS may or may not have enough range of adjustment to restore the off idle response under load.
Does it just BOG when you try to give it throttle?? the problem with pods is not so much the air volume but the air flow..
Particularly at idle speeds, the air volume or flow is unchanged between pods and the stock induction. Such volume or flow is determined by the volumetric efficiency of the cylinder, which is unchanged with an induction mod. There may be differences in volume or flow up near red line RPM, though.
a STOCK air box is shaped in a way to cause the air to vortex and cause LOW pressure in the carb throat which in turn causes vacuum.
A velocity stack open works BETTER than the pods because they cause the air to be pulled directly in to the carb throat, the air through pods have to flow from the side of the carb to get in the throats. You want really find out about PODS, get the bike running decent with them and ride with your legs tucked in against the tank ,then spread your legs out in the airflow and see how the bike acts .
You may wish to review your theory of operation about this. I won't pick it to pieces here. I'll just say it appears very "creative".
There is really only one driving force causing fuel to pass from carb bowl to carb throat, and that is air pressure differential. Differential pressure comes from two sources, the falling piston on the intake stroke, and venturi effect when there is enough velocity to produce a pressure drop from forcing an air speed increase through a restriction.
I will say that while the main jet does supply the throttle valve (Slide needle), the main jet performs no restriction on fuel mixture until the slide needles have been raised to the 3/4 or more position. Mixtures below these throttle positions, are restriction metered by the throttle valve diameter and taper, variable with slide position.
There are, of course many other tuning details within the carbs, but the ones mentioned are the major ones who's concepts should be firmly grasped first. Discussion of those is more appropriate when it is known which model carb is being discussed.
