NGK Iridium Spark Plug - BR9EIX

The NGK Iridium IX BR9EIX (3981) is a high-performance spark plug specifically engineered for 2-stroke and high-revving performance engines.

It is a popular choice for performance enthusiasts because the 0.6mm laser-welded iridium tip requires less voltage to create a spark, which leads to better starts, more efficient combustion, and a noticeable improvement in throttle response.

Key Specifications

• Heat Range: 9 (Cold)

   

• Thread Diameter: 14mm

   

• Reach: 19mm (3/4")

   

• Hex Size: 21mm (13/16")

   

• Gap: 0.8mm (0.031")

   

• Terminal Type: Removable Nut

   

Performance Benefits

• Anti-Fouling: The Iridium IX series features an extended insulator nose and corrugated ribs to prevent "flashover" and carbon buildup, which is critical for 2-stroke engines that run oil-fuel mixtures.

• Durability: Iridium has an extremely high melting point (over 2450°C), making it 2–3 times more durable than standard nickel or copper plugs under extreme heat.

   

• Corrosion Resistance: It features trivalent metal plating, which provides superior anti-corrosion and anti-seizing properties, ensuring the plug doesn't get stuck in the engine head over time.

Popular Fitment & Compatibility

The NGK BR9EIX is widely used across various performance platforms:

• Off-Road: Yamaha YZ125/YZ250, Kawasaki KX125/KX250, Honda CR125/CR250, and KTM 250/300 EXC.

• Street/Scooter: Aprilia RS 50/125, Cagiva Mito 125, and Gilera Runner 180 (2-Stroke).

• Classic Performance: Often used as a performance upgrade for Royal Enfield Bullet models and older air-cooled performance bikes that require a colder heat range.