Well for the most part it is. It had originally over revved, and then started to smoke . I had removed the breather assembly to make sure it was ok, and evidently got one of the pieces turned upside down. I found that the hole in the bottom of the valve stem housing of the cyulinder assembly is off to ne side more than the other. Also the inlet opeing on the inner portin of the breather is on one side, and the reed and outlet on the opposite. The breather tube is also on one side more than the other, and its also higher up from the center line as well. Its possible to put this assembly back a couple of different ways, when you consider you can turn the inner chamber portion two different ways and the outer cover two different ways and the entire assembly 2 different ways. I found that by placing the oil drain hole in the valve housing area as far away from the inlet opeing in the breather inner section and then placing the outer cover opposit that hole and with the rubber vent hose being placed in the above center positon it reduced the smoking a great deal. This evidently allows it to breathe, but creates a longer and more restrictive path until it vents to the atmosphere. Now it runs fine, and will run without any smoke for about 30 minutes then it will start to put out a bit of blue smoke from oil, and then it will continue on running free of blue smoke for about 30 or so minutes then make a puff or two of blue smoke again. At least its not loosing or burning up half a crankcase of oil in 30 minutes or running now. I still think I am going to rering it and hone it, and take whatever results I get from this rering job and be satisfied all internal parts are ok.