This is our ProBld Ultimate Performance Cylinder Head Kit. This sucker is a must if you are running a 180cc(63mm) - 232cc(67mm) big bore cylinder on your GY6. This will allow the engine to start without any issues.
As you may or may not know already, these big GY6 motors struggle to start. There is far too much compression. Even with a strong lithium battery and a high torque starter, it’s a struggle. This kit solves that problem. The ProBld Ultimate Performance Cylinder Head kit comes with a J-300 camshaft (good for mid to high rpm), machined rocker assembly to fit the decompression camshaft, cylinder studs, exhaust studs with nuts, intake gaskets, velocity stack, and of course the performance cylinder head with a giant 30.5mm intake valve and 26.5mm exhaust valve. It doesn’t get any better :-)
We offer this kit for both GY6 A (54mm stud spacing) and GY6 B (57mm stud spacing). The GY6 A head kit is to be used only with 63mm cylinders. The GY6 B head kit is to be used only with 65mm-67mm cylinders. Choose your kit in the drop down at purchase.
