Okay, I'm a dummy--put another carb on it this morning and it worked great--definitely a carb problem. Went on the Zama site, looked and read about their rotary carb--then thought about everyting I had done--okay here's where I'm a dummy. I had removed the plug so I could adjust the high speed jet--or so I thought. This plug was a small plastic cylinder with an o-ring--definitely different than the kind that need to be drilled out. As it turns out, this Zama RB rotary carb has a fixed jet in it, and the plug I removed was allowing it to suck air straight from outside rather than fuel. Put the plug back in, changed the carb out for about the 10th time, and it starts and runs. Okay, another lesson learned. Good thing I was working on my own equipment since I now have about 20 hours into this "simple" maintenance job of replacing tank grommet and fuel lines and filter--and what I thought was going to be a tweak of the high speed jet.