As the piston approaches top-dead center, the mixture is ignited by the spark plug, and when the fuel vaporizes in the cylinder, the air and fuel mixture is cooled. 由於活塞的辦法頂端死中心，混合物點燃的火花塞，當燃油蒸發在汽缸內的空氣和燃料混合物冷卻。
The idle system supplies a very rich mixture to start with. 怠速系統提供很濃的可燃混合氣供起動使用。
The ignition system provides high-voltage electric parks that ignite, or set fire to, the charges of air-fuel mixture in the engine combustion chambers. 點火裝置產生高壓電火花，從而使發動機燃燒室中的可燃混合氣起燃。
