Sorry to hear about your luck. It is unfortunate when members spend good money to get a project going and issues like this keep coming up. I do remember reading a thread not too long ago about a bad Carroll Stream engine. Out of curiosity, were the engines being run governed or ungoverned? Also, how different are these from the duromax engines I read about members using? It is good to have a nice source for cheap engines for low budget projects. I believe these clone engines do not get as detailed attention during their build process as the name brand engines. My dad got a cheap harbor freight engine to replace a blown push blower motor, and I had him run it for a short bit and then change the oil to get any machine shavings possibly left in the engine out. Maybe it was a waste of oil, but I felt it was a good idea and knew it wouldn't hurt anything.
l like to buy stuff and no I don't do payments!