N-MP-094996-A CYLINDER HEAD 63MM GY6 Requires N-MP-09499-6 CYLINDER KIT 63MM GY6 UPGRADE Excellent upgrade for GY6 based ATVs, Go Karts, Scooters, Motorcycles and more. More than likely you will need to bore out the engine casing to install this upgrade. Some ATVs do not require boring, but most scooters, Go Karts, and motorcycles will.