NGK Spark Plug Caps are designed to reduce “Electro Magnetic Interference” and “Radio Frequency Interference” which can interfere with electronic ignition components causing misfires and poor engine performance.     Figures: (top Left) show a damage NGK Spark Plug Cap, (bottom left) close-up photo of damage spark plug cap, (right) an image of motorcycle engine … Continue reading Spark Plug Caps are also IMPORTANT!