NGK Iridium IX Spark Plug CR9EIX

NGK 3521 CR9EIX Iridium IX Spark Plug

Boost your personal watercraft's (PWC) performance on the waves with the NGK 3521 CR9EIX Iridium IX Spark Plug, a top-tier upgrade designed for marine enthusiasts and demanding jet ski applications. Part of NGK's acclaimed Iridium IX series, this spark plug offers exceptional durability, reliable sparking, and improved fuel efficiency, making it perfect for PWCs like Kawasaki Jet Skis and Yamaha WaveRunners. Its advanced iridium construction and fine-wire electrode ensure consistent starts, smoother acceleration, and efficient combustion even in harsh marine environments, helping you maximize throttle response, reduce fouling, and extend service intervals while enjoying longer rides with fewer interruptions.

Key Features and Benefits

• Iridium Alloy Center Electrode: 0.6mm fine-wire iridium for heat resistance and long life (up to 50,000 miles). Provides precise sparks for better ignition in high-rev PWC engines.
• Pure Copper Core and Advanced Design: Excellent heat dissipation to prevent overheating. Tapered ground electrode for better fuel burn, more power, and lower emissions in four-stroke motors.
• Built-in Resistor: 5k Ohm resistor reduces electronic interference, keeping GPS and onboard systems clear in wet conditions.
• Heat Range: Rated at 9, ideal for medium- to high-compression marine engines during high-speed runs.
• Corrosion-Resistant: Nickel-plated shell and ceramic insulator protect against saltwater and moisture for reliable marine use.

Technical Specifications

Compatibility and Installation Notes

The NGK 3521 CR9EIX serves as a direct upgrade or replacement for many PWCs originally equipped with CR9EK or similar plugs, enhancing performance in four-stroke engines. Common applications include:

• Kawasaki Jet Skis: STX-12F (2003-2007, 1200cc), STX-15F (2004-2015, 1500cc), STX (2009-2010, 1500cc), Ultra 250X (2007, 1500cc), Ultra LX (2007-2015, 1500cc), and models like Ultra 300X/310 (as an alternative for improved ignition).
• Yamaha WaveRunners: VX1100 VX (2007-2019, 1100cc), VX1050 V1 (2016, 1050cc), FX160 series (1100cc), JetBlaster (1050cc), Super Jet (1050cc), and similar four-stroke models.

Always verify fitment with your PWC's manual or NGK's application guide. Installation is simple using a 5/8-inch spark plug socket and torque wrench; apply anti-seize to threads for aluminum heads to avoid seizing in marine conditions.

With NGK's legacy of quality since 1936 and proven track record in marine applications, the CR9EIX Iridium IX Spark Plug is more than a part—it's your key to unleashing reliable, high-octane fun on the water.