Ummmm.....Pistons still have rings that need to be seated properly. Do not hold your throttle wide open for more than a couple seconds for the first little bit. Get them hot, then let them cool. As you burn more fuel, you can increasingly stay tapped to the bar. But you cant just take it out of the box and drive it like you stole it. Engines still have to have proper breakins. Take it from a mechanic.