Thought I'd quickly share a related experience. My EU6500is (which I use as a backup gen) was running poorly -- constantly hunting and I often couldn't run it in eco mode. I had the carb service/cleaned twice over the course of a couple years. It got bad again recently and instead of having it serviced again, I decided to tackle it. I cleaned it using all the tricks in this thread several times. That improved it, but I still couldn't stop it from hunting or from bogging and dying in eco mode depending on the load. So, for $30-40 I bought a carb kit (all new parts including o-rings etc) from a local Honda dealer (you can also do it online). Once I got the right jet size (I'd ordered one that was too large initially), the thing ran better than new. I couldn't believe it. I can run it in eco mode and instantly turn on 3kW of load (from 0 load) and it manages it PERFECTLY. Unbelievable. I can't overstate it.
I, too, was intimidated by touching the carb of such an expensive machine but a) I was now out of warranty and b) there were enough videos online to help me through it. Turned out to be easier than I thought and the results were far better than I could have ever hoped for.
