The trick is to get the liquid even in the tube at idle and then to stay that way when throttling up. Adjust the cable fittings on top of the carb to do this. At idle if the oil is high on one side that means that side has the throttle slide too low so screw in on the idle speed screw or screw out on the other carb. When throttling up if one carb has high oil it is opening less than the other side so screw out on its cable adjuster. This works really well and works just as well on 4 carbs. Just use 4 tubes all tee fitted together at the bottom.
Here is a video showing how it worked.