NGK CR9EIX Iridium Spark Plug – 3521 The NGK CR9EIX is a premium iridium spark plug engineered for long life and consistent performance. Featuring a fine-wire 0.6mm iridium center electrode, it improves ignition efficiency and throttle response. A tapered cut ground electrode reduces quenching, and the high-alumina ceramic insulator offers durability under high-heat and vibration conditions. The CR9EIX is a popular upgrade over standard copper plugs in many modern sport bikes and dualsport motorcycles. It provides strong spark energy, excellent resistance to fouling, and reliable performance in demanding riding conditions. Specs: Thread Size: 10mm Reach: 19mm (3/4") Hex Size: 5/8" (16mm) Heat Range: 9 (NGK scale) Electrode Material: Iridium Resistor Plug: Yes NGK Part Number: 3521 Common Fitment: KTM 690 Enduro R / SMC R (2008–2024) Yamaha WR250R / WR250X (2008–2020) Honda CRF250L / CRF300L Kawasaki KLX250 / KLX300 Suzuki DR-Z400 Always verify fitment with your motorcycle’s service manual before installation. Cross Reference: Suzuki U27ESR-N - 09482-00459
