This thread -
clicky covers a cleaning/rebuild, but is what I used to learn how to change the jets in my EU2000i.
I live at 2,500', but all my dry camping reservations for the next few months are at 7-10'K. So last week I changed my jet to be on the safe side. It was the third time I've done the job and didn't need the photos and was done in under 30 minutes.
It is less work than the thread I linked to, as you don't have to get the carb fully disconnected from the unit.
A big part of why I bought the Honda over Champion (or even the Smart-whatever Costco genny) was so I'd have easy access to parts, especially the high altitude jet.
2013 Heartland North Trail 22 FBS Caliber Edition
2013 Ford Expedition EL with Tow Package