Why did you set the idle mixture screw to 1 turn? For the WA, the manual says start with both idle and high speed needles set at 1.25 turns. At that adjustment the H needle should be somewhat rich, and when you tune it properly you'll probably end up at about 1.125 turns if the metering lever height has been set accurately.

Getting those little engines to idle is an art, especially if you have the bad luck to have an engine with a slight crankcase leak, though in that case it will probably be quite difficult to start as well. Just set the idle speed high at first, and follow the instructions. These are for the WA:
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