On the evolution .36 piston there is a portion of the bottom circumference of the piston that has a slight upward curve to it as seen in the picture below. When I disassembled the head and pulled the crank shaft out, I failed to notice whether this curved area was facing to the front (towards the carb) or to the rear(towards the backplate). I cannot tell for sure, the piston will go in either way, in the picture the curved area is right in front of the camera, facing to the rear. You can see it clearly in the picture below. Anyone know? I can get it back together no problem, I just want to be sure that I have the piston oriented the right way.