We had a 2k gen made by Smarter Tools which, like yours, utilized the Yamaha 79cc motor and it proved to be vastly underpowered, especially at altitude. Wound up having to get a second one and paralleling them together which was a PITA having to care for two gens instead of one. When Honda released the EU2200i with it's powerful 121cc motor, I jumped on it and sold the two Yamaha knock offs. Haven't had any issue running anything ever since, even above 6,000'.