RX is a horizontal needle, and the heat is 5 as the original factory. HX aimed at the needle, but the heat was 6. The gap of spark plug has a great influence on performance and fuel consumption. The larger the spark plug gap, the lower the fuel consumption when idling or congested. However, the fuel consumption of spark plug with small clearance after 2000 rpm is lower than that of spark plug with large clearance, and the ignition success rate of spark plug with small clearance will be higher and the power will be better after 2500 rpm. Spark plug is an important part of the ignition system of gasoline engine, which can introduce high voltage electricity into the combustion chamber, make it jump over the electrode gap to generate sparks, and thus ignite the combustible mixture in the cylinder. It mainly consists of a connecting nut, an insulator, a connecting screw, a center electrode, a side electrode and a shell, wherein the side electrode is welded on the shell.