For the most part of gas scooters come with air-cooled two-stroke engines with automatic two-stroke oil injection, although some of the higher-end scooters, such as the Honda FC50 and Yamaha YQ50, are water cooled. But scooters increasingly have four-stroke engines (the Honda GY6, for example) to meet stricter emissions controls. For more details visit us at http://www.gsmotorworks.com/