I will never own another Yamaha generator after owning both the 2800i and the the 1000i. They will have carb issues regardless even if you run the gas out and run a fuel stabilizer. I do however own Hondas that start/run on two year old gas without an issue.....
Anyway, now for the fix. Both of my Yamahas had issues with a jet that is above the fuel bowl in the main body and seemed to corrode inside even when the fuel was shut off/run dry before storage. At first I would pull the carbs, remove the bowls, and clean everything, but never really found anything. Start them up and they ran horrible...until I found this little jet in the main body that needs to be cleaned with a super small wire. For the 1000i, I had to cut a fine hair from a stainless brush as it was the only thing I could find small enough to fit! If I remember correctly, I didn't even have to pull the carb completely to remove this jet.
Not really a brand complaint, but it appears that the particular carb Yamaha uses is the only one I have seen with this jet. Hoping this helps you and others who would otherwise miss it......I know I did and I have worked on small engines and motorcycles my whole life.
Here, I found a pic on the net...... It's the little brass jet under the screw with the spring on it.
Edited by CrazyCooter, 04 January 2017 - 10:40 PM.