Even if you do not understand this you should not ignore this.
Originally Posted by
Roelof
When the piston gets real hot the molecules inside will will slightly change the material and give a permanent grow. It is a part of the break in and why there is a heatcycle methode as one of the many break in methodes..
It is a process every metal knows when heated up and cooled down. Then the material does not get heated up more then it will stay the same size, but when you go to lean on an engine, making it hotter dan used before, then the next day you will feel a higher pinch again.