I have a Honda generator which stood for 5 years with not being started. My fault, I left the old gas in there and did not lay it up or anything. Needless to say this year it would not start at all. I removed the carb and found some serious goop totally clogging all the internals. Tried dismanting and carb cleaner etc etc.
Nothing I did would make the damn thing start, it tried to sputter a few times but would not stay running. I researched a little (mostly on Motorcycle websites) and I found a few suggestions of soaking the whole carb in Pine Sol for a day or so and apparently this would clean everything out. Well, for a couple of bucks compared to a new carb it was worth a try I thought.
Left it soaking undiluted for a week, then made a 50/50 mix of Pine Sol and water, soaked it for a couple more days then washed the whole thing in the sink with Pine sol. To say it came out looking brand new is an understatement!
Re - fitted it, started up on the second pull! Runs perfectly now - No joke.

Apparently it has to be genuine Pine Sol and not any "own brand" types.
Smells good too!