pinch off the fuel line to the carb, if it dies right now your too lean..if it runs for awhile then your too rich....if after a few seconds it speeds up and starts to die, or dies you're ok..rightie tightie leans it leftie loosey richens it.
also check your muffler to make sure you dont have something causing excessive back pressure on the engine..if for instance the wrong size exhaust deflector or the wrong muffler. perhaps try taking out the baffle