Try 1-3/4 turn instead. 
Hmm... As the adjuster screw is on the ntake side of the carb, I was under the impression that it controlled the amount of fuel (i.e opening more is more fuel, less air) and not the amout of air (i.e.more air, less fuel), no?
Well...common misconception, really. The little screw adjusts the AMOUNT of air-fuel mix that is admitted: the pilot jet adjusts the RATIO of fuel-to-air.
While it seems true that 'downstream' screws might adjust fuel instead of air, this sort of thinking seems to come from things like lawn mower and weed-beater carbs, where the screws often DO adjust the amount of fuel admitted to the passing airstream, as these machines often have pumper-style carbs - especially the 2-strokes. In those, yes, the screw does affect the fuel. Four-stroke mowers with just 1 screw often meter ADDITIONAL fuel to a fixed-orifice arrangement nowadays, in the interests of limiting emissions, but the base-fuel mix is fixed by jets (or drilled holes).
In these carbs, the pilot jet controls how much fuel is mixed with the air that is coming into the emulsifier (that's those tiny holes in the little tube in the tip of the pilot and main jets) and that air ratio is fixed: the pilot jet then admits [metered by hole size] fuel into that airstream, and the external "idle mix" screw determines for HOW LONG the fuel is fed into the engine during the intake stroke. In between each intake stroke the air pressure in the intake manifold rises suddenly (the intake valve shuts off that airflow) and this pulse pushes the fuel-air mix back down the pilot jet's emulsifier. As the RPM increases this push-down becomes less and less so the pilot system is constantly feeding at about 1800 RPM, until the main slide opens far enough that the airflow is no longer laminar across the top of the pilot jet's opening, and it stops pushing fuel up toward the throat by about 2200 RPM.
So...the idle-mix screw is a timing device more than anything, adjusting how long the pulse of ([#40 hole fuel] + [air admitted at the back of the carb's pilot air port]) will actually happen. Opening it more will start the feed a little bit sooner by restricting the air-fuel mix less: closing it more will shut if off sooner by restricting the available volume of air-fuel mix. Hence, it runs richer as the screw opens more - until the max flow possible is reached.
Deep in the weeds, to be sure: but this is how all these carbs actually work.
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Deep in the weeds is where it gets interesting, thanks for that!
So, if you are suggesting to try 1&3/4 instead of 1&1/2 then that means richer...if we have too much fuel vapor being pushed into the cylinder, wouldn't we want to lean it out?
On a separate note, I spent a few hours dialing in the carbs as best as I could. We are just under the seam on all four now. Was having some issue with carb 3 puking out fuel (from everywhere) every time I did the clear tube method... Couldn't figure out why that was happening. Carb doesn't leak otherwise, drains if I open the drain, and holds the fuel if I close the drain. Only happens when I bend the clear tube upward and open the drain.... In the end I was able to get a proper result on the clear tube, but the whole set up is unstable for some reason. Anyway, I cleaned the drain tube with carb cleaner before reinstalling on the bike for good measure. Not sure this is related to the issue at hand though (probably not I suppose).
Started the bike just for a minute, smoke from the breather and exhaust again. Will let it heat up to operating temp tomorrow, and report back.
