It's a ported and decked 69cc, PK80. It's the one with the shorter connecting rod and the lower wrist pin location on the piston. It's a 40 stroke and it has a .6cc Fredhead clone high compression head and a CDH-G2 4 peddle reed valve w/windowed piston and a dellorto clone carb. The reed valve is the newest addition, I just put it on last week!
@Tyler6357 Cool! I'm not even a small time mechanic so I don't understand everything in your description but it looks like a nice powerful little engine there. I'm looking to upgrade my expansion chamber with a dirt bike pipe as well.