Iglobalbuy 26" or 28"Bicycle 80cc 2 Stroke Motorized Gas Engine Motor Kit The 2-stroke petrol engine mixing Ratio of Fuel(90#) and Engine Oil: 16: 1 for New sets, 20: 1 after Running 500Km. This 50cc/80cc bicycle engine easy to install. The rider only needs some basic hardware skills, tools, and fine tuning adjustments (Note: Seller is not responsible for misuse or this kit or any warranty after installation). Fits Most 26"&28'' Wheeled Bikes (Mountain, Cruiser, Chopper, Road) with V-frame. The frame should have 9-11" of clearance between the bottom bracket and top bar, and the diameter of the frame tubes should be 25-29mm (around an 1"). To start the 2-stroke engine, move the choke lever to "on" position, hold in clutch, pedal the bike to get some speed, and then release the clutch gradually. To stop the 2-stroke engine, choke the carburetor completely with the lever on the carburetor. Alternatively, slow speed, hold in clutch and press the kill switch on twist-grip throttle.6. If you want to use your bicycle as a common bike, just disengage clutch, then press the silver button at the side of clutch, the motor will not be started.