Is this "surging" the RPM rise and fall that ONAN calls "Hunting?"
When we had a BFA, I tried several times to clean the carb. I'm pretty good at small engines, but I could not get it to run right, and turning the High Speed adjustment didn't cause anything to change.
I was lucky enough to find one of the few-and-far-between shops who would clean small carbs electronically. It was about 90-pct better, but still had a "hunt" to it. The manual had troubleshooting for hunting that included cleaning the governor cup and a couple other invasive steps. Then, replace the Governor Spring. DW persuaded me to get a Spring. I was already going to ONAN for some gaskets.
The Spring replacement cured that last little bit of Hunting.
