This brings up an interesting point I'd like to share; Piston Pin direction on Rear Exhaust engines. One end of the pin is hollow and the other end is capped or solid.

I've seen them installed both ways on various models of Rossi, YS, and OS engines.

I always install them with the hollow end to the rear in a Rear Exhaust engine. BECAUSE the piston pin is lined up with the boost port at a time when you are trying to build crankcase pressure and any volume in the pin tends to reduce crankcase compression ratio.

I don't think it effects lubrication one way or the other.