Where is the spark plug located on a underbone motorcycle?

[VanKylie]

The spark plug on an underbone motorcycle is installed on the cylinder head of the motorcycle. Working principle of the spark plug: Under high voltage, the air between the center electrode and the side electrode of the spark plug rapidly ionizes, forming positively charged ions and negatively charged free electrons. When the voltage between the electrodes reaches a certain value, the number of ions and electrons in the gas increases like an avalanche, causing the air to lose its insulating properties and forming a discharge channel between the gap, resulting in a "breakdown" phenomenon. At this point, the gas forms a luminous body, known as a "spark." Along with the thermal expansion, a "crackling" sound is also produced. The temperature of this electric spark can reach as high as 2000-3000°C, which is sufficient to ignite the air-fuel mixture in the combustion chamber of the cylinder. Damage to the spark plug may result in the following situations: difficulty starting, reduced power, excessive exhaust emissions, and increased fuel consumption. If these symptoms occur, the spark plug should be replaced promptly.