"iwdplz" wrote in message
...
The interesting thing is that all 3 of these engines would run great under
normal load (while cutting grass, while pumping water, while spraying).
The fluctuation only happens at idle or under non-operating load.

I have a 5 kw generator with a Tucumse engine and it does the same thing.
It will surge under a very light load or no load. Put about a 1000 watt 120
volt load on it and it runs smooth.