From looking at your photo one would surmize you take that thing anywhere there is a BUMP to hit.. It is highly likely you have slightly bent the float hangers from these bumps and the bowl level is too deep! This will cause all the problems you describe.
Remedy: Take the top off of the carb and observe the float level.. If an old rebuild kit is available (I save many of the old used kits) apply the measuring device to the float to see if it has indeed changed positions. Bend the hanger to acquire the needed level.
Big JIm
<img src="/forums/images/graemlins/pfft.gif" alt="" />