Sounds like your needles need adjusting as the high seems too lean. I have used this carb in testing and have had no issues running upright or inverted. Mine is mounted inverted on the DVIII I am building. I also started with a WT carb with external pulse but the pulse line filled with oil and caused me issues. The high needle is to the right and just above the fuel inlet barb. The low is on top of the barrel and to the right of the swivel for the linkage. Look at my pictures to see what I mean. I used the stock swivel to attach my linkage to, worked well for me. I also made a manifold to rotate the carb for a straight shot linkage. So far so good. What I found when adjusting the low was to fatten it until I had a little black smoke then lean it down a bit. Tuned the high until it just stumbled at WOT then fattened it up a bit. Ran it many times in testing to fine tune and no issues to date. You will also know when it is rich on either end because you will smell like a bad running lawn mower in short order. These carbs and more important these engines tune a little different than the two strokes we use. What button are you speaking of?