Mikuni jetting and tuning issue

I have a '73 850 commando with a just installed brand new single VM34 carb. Initial specs were: Main-240, Needle Jet-159 P0, Needle-6DH3, Air Jet-2.0, Pilot Jet-40, Slide-3.0, Air Screw-2 1/2 turns out. Bike started ok with these parts. Used choke to start. Had to leave choke on for at least 10-15 seconds or else the engine would die. Adjusting air screw would not significantly increase RPM's. After warm up rode bike but never got past 1/4 throttle. Engine bogged down and died unless I backed off on throttle. Pulled clutch shut off engine and inspected plugs. Severely carbon fouled. Went to #35 pilot jet. Same thing. #30 P.J. same. #25 same. Any throttle past 1/4 produced bogging and engine dying. Mixture obviously too rich. Tried a 3 !/2 slide. No difference. Even though the Needle jet and Needle don't become a factor until after 1/4 throttle I tried a 159 O/0 jet with needle clip 2 notches down from top anyway just to see. Nothing or any combination of jetting or settings has gotten a smooth transition past 1/4 to 1/2 throttle. Engine always bogs and dies. In addition plugs are always black. I also noticed that the pipes turned blue after multiple starts trying to figure this out. From what I've read this a sign of a hot running engine most likely caused by a LEAN mixture. Between carbon fouled plugs (RICH) to blued pipes (LEAN) to multiple jetting and setting combos I'm at loss. Any help in figuring this out would be hugely appreciated.
Current parts are Main-240, Needle jet-159 O/0, Needle-6DH3 (2 down from top), Air Jet-1.5, Pilot Jet-32.5, Slide-3.0.

What air cleaner are you using?

Go back to the P-0 needle jet and 340 pilot. Use the 2.0 air jet.
I am guessing that there is something wrong with choke valve. Pull it out and carefully inspect. It may need replacing altogether. A new one is about $15.
Your original jetting is very good. The only other supply of fuel is the choke.
Check float level.
Remove the air cleaner and see what happens. It would have to be REALLY clogged to produce the results you're talking about.

I meant the #40 pilot.

Check the enrichener plunger seal, and adjustment, that it is seating properly.

Also check for foreign material in the air passage from the air horn to main well.

If you put the clips in the top position on the needles, when you open the throttle the engine should miss badly. If it doesn't , your needle jet is either too rich, or the enricher is staying open. The correct position for the clips on the needles is one notch below where the miss begins to appear - lower the needles until you get the miss, then raise them one notch. If the idle is OK, the low running circuit is probably OK. The normal slide for most carbs usually is number 3 - it indicates a cutaway height of about 3mm. Sometimes richness is due to a float problem.
If you think about it logically, you should be able to fix the problem quickly. All of the jets meter the fuel supply except for the air jet in the slow running circuit. Start rich- then lean-off. If the motor idles, the air jet is probably OK. There are usually 3 parts - idle to quarter throttle, midrange, then 3/4 to full throttle. Above 3/4 throttle, it is wise to be slightly too rich. For performance, the mid range mixture control is critical.

Unless the main jets are miles too small, they do not usually affect the other jets.

Here are my settings. I think I went down to a #30 pilot since.
Your slide cutaway is 3.0 while mine is 2.5 so when you crack the throttle, it gives a little more lean than mine.
But I don't know enough about Mikunis to say whether this could be a factor

As Concours suggests, pull the carb and check the idle circuit that has has an air feed in from the main
horn and then meets the fuel coming up in a tube from the float bowl that through the idle jet and then continues in the passage to come out of two holes downstream of the slide. I would suggest to take out the idle jet and clean.
Also check the float fuel level setting and that the float is not sinking and that the float needle valve has no restriction.




Slide 2.5 cutaway
Needle 6Dh3 (It is set to the middle notch)
Main Jet 250
Pilot jet VM20/210 #35
Air jet BS30/97 #2.0