The part I can't understand is about the bottom of the piston skirt CLOSING the exhaust port.. Most 2 strokes are made so that the top of the piston is just flush or a little below the bottom of the exhaust port...The piston skirt does nothing about exhaust timing...If cutting the bottom of the port makes it run better, it's more from making the port slightly larger than anything else...You would do more by slightly widening the port or slightly raising the top..