Hello, just wrapping up the inspection, cylinders 1 and 2 spark plugs were black with a good clean electrode, cylinders 3 and 4 very clean like they never have been firing. Engine has 27 hours on it and develops full power. Is this normal since the front 2 cylinders probably get better cooling and the back two cylinders run hotter. Maybe a mixture problem or nothing at all. My first time inspecting plugs on a rotax, any comments. Thanks Don