The 48cc cylinder body perfectly fits the 2-stroke 48cc bicycle engine kits. The engine has been designed for Grubee, Mega motors, a flying horse, and other RAW 48 cc engines. The studd size is almost 6mm. 

The installation of the system can be done easily and quickly. You have to begin by unbolting and removing the head cap of the cylinder. After you have removed it, lift the cylinder over the piston. You have to replace the bottom of the gasket and lubricate it lightly with the 2 stroke oil. 

Install cylinder over the piston and then re-install the cylinder's head back to the cylinder when you are ready for riding a bike.

Part #5 on the Cylinder Head Diagram