If your looking for a quality, simple. and effective big bore/cam/head package for your 150cc gy6, look no further. This setup requires ZERO machine work.
This setup includes the following
61mm big valve cylinder head
61mm 171cc cylinder kit complete with all gaskets/piston etc
High lift race camshaft
Intake Lobe 26.25mm
Exhaust Lobe 26.15mm