Your 'lawn-boy' doesnt have an 'emulsion tube' inside the carburetor. Emulsion tubes are commonly used in many small carburetors to control the air/fuel ratio.I don't buy the "bad Gas" excuse!!! I use the gas for my lawnboy 2 cycle( read that as made by the outboard motor people) mower from season to season with no trouble. I clean the air filter once each year and shove it into the shed when I am finished. I can't recall the last time I changed the spark plug. It always starts on the first or second pull and has for 15 years.
Carburetors without emulsion tubes have difficulty in controlling their fuel/air ratio and usually burn 'very rich' at near WOT.