Bore and Stroke: 50mm x 40mm; Better adjusting clutch a little before riding. Excluding manual; Cylinder head and Cylinder two in one piece; 50mm bore; Improved magneto as well. Cylinder inner diameter 50mm; Piston outside diameter 50mm; 8mm front and rear mount studs; 40mm alum intake stud spacing.The item "JZsports 2 Stroke Yd100 Motor-Silver Color Engine-Gas Motorized Bicycle" is in sale since Wednesday, January 13, 2021. This item is in the category "Sporting Goods\Outdoor Sports\Scooters\Gas Scooters". The seller is "jzsports-2019" and is located in Tucson, Arizona. This item can be shipped to United States.