Brand new BT100 100cc complete 2-stroke engine kit. This engine kit features a single piece cylinder with open transfer ports, silver metallic enamel finish, and fantastic performance. Please take the time to read the break in procedures below! BT Super Sport Complete 100cc Motorized Bicycle Engine Kit Includes: 100cc BT engine (78.6cc actual) 3 HP+ - Average Power Bore and Stroke: 50mm x 40mm Three Ring Piston with low wrist pin and short connecting rod Open Transfer Port Single piece cylinder Large 45mm Exhaust Port Standard NT racing carburetor Chrome muffler - with clamps and copper gasket Standard CDI and spark plug 2 Liter Black Teardrop Fuel tank ? with mounting hardware, fuel cap, fuel valve, inline fuel filter, and fuel line Twist throttle with kill switch - with matching left grip and gooseneck style throttle cable Quick release push button clutch lever - with clutch cable 44 tooth rear drive sprocket ? with standard rear wheel installation kit is standard. 36 tooth is available upon request 415 Heavy duty chain, chain guard, and ball bearing chain tensioner Large front mount for bicycles that have large down tubes Recommended Break In Procedures Add only professional synthetic 2 stroke oil The ratio of mixing engine oil and gas fuel must be correct 0-50 miles: 8oz per gallon 50-100 miles: 6oz per gallon ≥100 Miles: 4oz per gallon You have to check the color of the electrode of spark plug to make sure the mixture ratio of engine oil and gas fuel are proper. If the electrode has black color, it means there is too much engine oil and you should decrease its mixture ratio. If the electrode has off-white color, it means the engine oil is not sufficient and you should increase its mixture ratio