ST 70 Carburetor Float Level

Does anyone know the correct setting for this? (Bike is 1972 Honda model, Eng No ST70E-120979, (Keihn Seiki Carb.) I keep finding different dimensions on the web, but believe it should be somewhere in the region of 16mm to 20mm from bottom of float to underside of gasket seal??????

I've been fighting with my Keihin for the past week and now it seems to work at least adequately.

The manual states 20mm and it seems to be working for me generally, although my idle (partial and WOT are ok) seems to be on the rich side no matter what I do with the airscrew. Might too high a float level cause this? I did try other (lower) levels but the carb had also other issues at that time (flooding, vacuum leaks etc.) so no actual data about that.

And about the procedure itself : (correct me if I'm wrong) The float level is measured from the carb body (where gasket is) to apex of the float when the float is just touching the spring loaded valve. So put the carb on table so that it stands on the intake-> float hangs freely and then push it to touch the needle and measure the distance apex-gasket.

and forgot to add this: Isn't it also possible to determine the float level by measuring the amount of fuel in the bowl i.e. empty the carb via the drain hose and measuring the volume giving that the bike is level/positioned so that carb really gives its last drop. This should be easy and fast way to check the float level and a well functioning stock carb should give adequate reference for fast troubleshooting.