You cannot run out the bottom carbs on that motor ,unless you are above 1800 rpm Make sure the airbox gasket is in good condition and the hose is connected to the crankcase
Make sure the snap ring is on tight and the knob is not pushing out. You may need to modify the adjuster I have never seen one that actually worked correctly. leeroysramblings.com has a lot of good info on those.
What happens when you pump th primer ball on the fuel line? Primer ball on correctly arrow facing motor? Try opening the low speed screw another 1/4 turn open.