It's to early for me to defend DL based on the performance of mine after just two tanks of fuel (after reading the two accounts - the one from Russia (looks like something got into the engine from the intake or was left in the engine from manufacturing), and the other one about the poor bearing or crank fit), but if DL USA is supposed to be the authorized (by DL) US importer, I guess he's the only one who is obligated to honor any warranty claims (providing the engine was purchased from DL USA). (But maybe I'm mistaken and DL USA is not the sole, authorized importer.) I was talking to a guy at our field just last night who bought his DL from somewhere else and he said it came with instructions written in Chinese and no spark plug. I may be speaking "out of turn" here, but if something goes wrong with that engine I think he may have a hard time with any warranty claims or support here in the states. And without support (from DL USA?), I don't know whom one would turn to.