Just preheat it to 105 degrees Celsius (220-225 degrees fahrenheit). make sure you measure it at the top of the crankcase, under the head and button. Also, make sure the engine stays in the 105-110 degree (Celsius) range during each run-in session. I recommend running a tank at this temp, then rotating the flywheel to where the piston is at BDC (bottom dead center), and let it cool. Reheat and repeat. Easiest way to accomplish this is to set both needles to flush and start at 1/4 to 1/2 throttle after preheating.