Pulled the new spark plug and it had a lot of carbon on it. Spark seems present but not great? Not sure what to compare it to. I do see spark. Engine temps do not seem to change it. The flywheel has a bit of surface rust.
This machine ran fine for years and even this year. Problem just started. Ran most of the day yesterday and we shut it off. Went to restart and problem developed. Enigne turns easily by hand no mechanical problems felt or heard.
At idle the machine runs smooth up through about half throttle. In the upper RPMs it develops the lope and seems to be missing. Smokes a bit at high RPMs as well dark smoke not white.