Does not really matter, in the past, almost all engines I ever saw came with the hole facing outward, but I've always put the hole to the exhaust for two reasons. One, like The Wingman said, it theoretically highers crank case compression and, more importantly, two the covered side is the heavy side of the pin, its good to put it in the shorter, lighter side of the piston to help that offset balance that the rod is always having to handle in the upper bearing/section.

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