I bought an old Powermate 3KW generator with a Tecumseh OHH55 5.5HP
engine that doesn't run as smoothly as I'd like, to me it sounds,
smells and the plug looks lean. The Date of Manufacture is 8068 which
appears to mean the 68th day of 1998, before gas contained 10%
ethanol. The carb looks like a Series 8, with no idle screw. The fixed
main jet is stamped 166.

Has anyone modified one of these to run better on modern gas? On other
old engines I back out the idle mixture screw, but this one doesn't
have one.

tia
jsw