OK so, another Sunday afternoon partly lost to working on the carbs. FYI these carbs are rebuilt and very solid. What I noticed was that the while running the motor the fuel on the left carb was noticeably flowing especially when I blipped the throttle you could see it coming through the jet, the right carb however had little fuel flowing which made me wonder if the jet and or flex tube were somehow clogged. I pulled the entire carb, broke it down on the bench, checked the centering of the jet to the needle and that was fine, pulled the flex tube and while it seemed clear I blew through it and it seemed to be a bit spotty, like a sputtering air flow which makes me think there is a defect. Unfortunately I cannot take the tube assembly apart so I ordered a new one. Aside from that the rest of the carb was really clean and tight. The needles are both KN and the jets are both .10.
So, if the fuel flows into the float bowl and flows through into the flex tube but does not flow through the jet, in spite of lowering the jet to get a richer mix, what could it be?

When you open the throttle, do both pistons move upward equally? If not, the idle adjustments need to be synchronized.
Did you check the float levels in each float bowl? Could be that one is higher/lower than the other.
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1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl

I did note there is a slight difference between float bowl height, yes both pistons in the carbs raised equally.

If your floats are of the adjustable variety, you may want to adjust them so that they are the same. I'm not sure if this would produce the problem you are experiencing, though.
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1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl

considering fluids seek their own level it might make a difference considering the fuel height to the bridge is critical for venture pick up especially with 2 carbs versus 1, thanks.

Mike;

Fluid level in jet will/should certainly be the same/very similar as in bowl for that reason, but under flowing conditions (when venturi vacuum is drawing it out) I would expect fairly similar flow...I've had the bowl sump be so full of tiny particulates that it impeded the flow through the jet tube...so I'd first check for equal fuel levels in jet tubes (remove dashpots and look into jet with a light), the check for a flow blockage in the jet tube.

Good Hunting!

Right, that's on my 'to do' list this weekend. Thanks for the tip and just to be safe I ordered a new jet/flex tube for that one carb, should be here by tomorrow.