Small Engine Tune-Up - What have I done?

Sorry if this is off-topic.

A 2500 Watt 120V generator (Powermate Proforce PM0102500) seems to
be working fine, but engine sounds a little rough. Why not touch up the
carburetor adjustment and see if that improves it?

First I turned the screw on the carburetor to the right. Some resistance
to turning, but absolutely no difference in engine speed or sound.

Then I turned the screw to the left. Screw is quite loose and still no
difference in the engine, but now I have gas leaking from the bottom of
the carburetor! I turned the screw to the right until snug, and the gas
leak has stopped.

There is no other adjustment visible on this carburetor. Is that screw
intended to drain the carburetor, or have I seriously messed up something?

The owners manual is no help. I searched the web for data, and only found
that the 5.5 HP engine was made by "Sumec". I gather that they make
motorcycle engines, but found no carburetor data.

Fred

 

*Sigh*

 

Mark-

Very interesting article. It reminds me of the Till Eulenspiegel story.
'The name "Eulenspiegel" literally means "owl mirror," and may refer to
the proverb: "Man sees his own faults as little as a monkey or an owl
recognizes his ugliness in looking into a mirror."'

Fred