2-3 turns depending on your setup. What muffler is it? If it's a pitts try blocking one of the stacks. You may have a fuel draw issue. If it's a fuel draw issue it won't richen up, that could be your problem. Do you have a pump or regulator? Or just use muffler pressure? How far is the tank from the engine? How high is the top of the tank with respect to the carb fuel inlet?