Oh, it's lean, all right. But why? You said you blew the carb out with air pressure, but that does not guarantee that it's clean. This all boils down to too much air, or not enough fuel. Since you seem confident that there is no air leak, chase the fuel concept. In addition to re-cleaning carb, pull the fuel line off the carb, point it into a catch can, and turn the fuel tap on. Ensure it flows well, not trickles. If it trickles, either the inlet screen (in tank) is clogged up, or the tap.