I have the little 2 stroke. It's not a high quality generator and I don't expect it to be. Per the online suggestions, I installed an NGK plug, replaced the fuel line and mix the oil at 32 to 1. It's been fine up until I broke the fuel shut off lever. I ordered another, which is just as poorly made, and backwards too!
The air filter is does not seal tightly and despite regular cleanings, it has dirt beyond the filter element. Probably best to run this unit on a box or stand. Otherwise it will ingest dirt.
The larger units use the same type of low build quality. Not awful, but certainly not robust.
Champion makes much the same product line, but they are built to better specifications.