Complete billet headkit for the case reed inducted engine found on '47cc' chinese import pocketbikes. Kit includes 44mm bore machined cylinder, billet head shell, choice of compression dome, gaskets, spark plug, & hardware. This will increase acceleration, offer better cylinder cooling, and look great! Note: higher compression domes offer more power, but require higher octane fuel. 13:1 dome requires 92 octane or higher. 15:1 dome requires 105 octane or higher. Select the actual size of your piston.