Ditchound,
If the carb is a Keihin PWK39 an easy way I use is to disconnect the fuel hose and put a new piece on (tastes better). Blow air through it (with your mouth) to determine where the float needle cuts off the air flow. Set the float height so that the casting line on the middle of the float is parallel to the carb body or just a touch lower when it cuts off the air flow. Hope this helps. Cam.