I have reassembled my cub engine after cleaning the valve guides, laping and adjusting the valves, setting the timing, setting the govenor and throttle linkage and checking all the electrical system. The engine starts on the first turn and runs for 1/2 minute at any rpm and then stalls. I restart it with 1/2 choke and it runs fine until I push the choke rod in. I rebuilt the carb last year and every time I ran the engine I shut the fuel off and ran it out of fuel. It never ran correctly as I had intermittent sticking valves. Several times over the last two years I have chased my tail trying to find various real and IMAGINED engine problems and gave up, leaving the Cub sit for a month or two before starting my search for a remedy again. All along the valves were the problem and I'm at the cusp of finally being ready to push some snow, but the carb/choke problem has me going in circles once again.
The fuel is fresh. The tank is clean. The fuel bowl is clean. Everything appears to be adjusted correctly. Please