Spark Plug Stock # 3689

The NGK Iridium IX spark plug (Stock # 3689) is a premium ignition component engineered for reliable combustion across a wide range of small engines, motorcycles, and automotive applications. This single spark plug is designed for users who demand consistent starting performance and fuel efficiency in demanding conditions. The Iridium IX series represents NGK's commitment to delivering factory-grade spark plug performance for both OEM replacement and aftermarket upgrade scenarios.

At the core of this spark plug's effectiveness is NGK's advanced iridium electrode technology, which provides superior durability and faster, more reliable spark initiation compared to standard copper plugs. The 14 mm thread size and 0.708 inch reach make it compatible with a broad spectrum of engine designs, while the tapered seat ensures a secure, gas-tight fit in the cylinder head without risk of cross-threading. The resistor design minimizes radio frequency interference, protecting sensitive engine electronics and ensuring clean signal transmission to onboard diagnostic systems.

Mechanics, powersports enthusiasts, and fleet operators rely on the NGK Iridium IX spark plug for both routine maintenance and critical performance tuning. Installation is straightforward—simply match the thread size and reach specifications to your engine's requirements, gap if necessary per manufacturer specs, and thread firmly into the cylinder head. At just 0.1 lbs, this compact ignition component is ideal for emergency kits, service technician vans, or stocking multiple units for different engines in your collection.