A 2500 Watt 120V power 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?
I've 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.