NGK Spark Plug Set LFR6A (Pack of 8) — 26.5mm Reach, 16mm Hex, 0.9mm Gap, 5KΩ Resistor

NGK LFR6A (6668) is an OEM-style V-Power spark plug set of eight engineered for high-performance personal watercraft, featuring a 26.5mm reach, 16mm hex, 0.9mm gap and a 5kΩ resistor.

These NGK V-Power LFR6A plugs are supplied as a genuine eight-piece set designed to replace worn or fouled spark plugs in a range of watercraft models (FX, FZR, FZS, VX, VXR, VXS). Built around NGK's v-cut center electrode, they aim to stabilize ignition and promote consistent spark delivery under marine conditions. The physical dimensions and resistor value match common OEM specifications for many two- and four-stroke marine engines, making installation straightforward for routine tune-ups.

Why choose NGK V-Power LFR6A for my watercraft?

NGK's V-Power design redirects the spark toward the electrode edge, which can help the flame kernel form quickly and reduce quenching at the spark site. That design, paired with correct reach and gap, supports reliable ignition across typical marine operating ranges. The 5kΩ resistor also helps suppress radio-frequency interference, useful for onboard electronics.

• V-cut center electrode promotes faster spark development.
• 5kΩ resistor reduces electrical noise to protect electronics.
• Exact fit dimensions (26.5mm reach, 16mm hex) for compatible models.
• Sold as an eight-plug kit for full-bank replacement.

How do I know these fit my engine?

Fitment depends on the engine's specified plug type and physical dimensions. The LFR6A 6668 has a 26.5mm (reach), 16mm hex and is gapped to 0.9mm; if your service manual lists those values for replacement plugs, this set is a match. Always compare part numbers or consult the manufacturer's fitment chart before purchase.

• Verify reach: 26.5mm is the threaded depth required by the cylinder head.
• Confirm hex/size: 16mm wrench fits the plug body during installation.
• Check gap: factory gap set to 0.9mm — adjust if your manual specifies otherwise.
• Cross-reference part number 6668 or LFR6A in your owner's manual.

What are the installation and maintenance tips?

Install with a clean thread and proper torque to avoid damage; NGK recommends tightening to the torque specified by the engine maker. Use a gap gauge to verify the 0.9mm gap and retighten after a short run if required. Replace all plugs in a cylinder bank at once to ensure balanced ignition behavior.

• Hand-start threads to prevent cross-threading, then torque to spec.
• Check and set gap to 0.9mm before fitting if needed.
• Replace the entire set (pack of 8) for consistent performance.
• Inspect for fouling or unusual wear during routine service.

Will these plugs affect electronic equipment or radio?

The built-in 5kΩ resistor is intended to suppress ignition-related radio-frequency interference that can affect sensitive electronics. While this helps reduce electrical noise, it doesn’t guarantee interference-free operation in every installation. Proper routing of ignition leads and adherence to the craft's wiring guidelines also matter.

• 5kΩ resistor reduces RFI/EMI compared with non-resistor plugs.
• Correct wiring and grounding enhance overall electronic stability.
• Not a substitute for diagnosing wiring faults that cause noise.

Who is this for? NGK LFR6A 6668 (pack of 8) is intended for owners and technicians who service compatible personal watercraft models (FX, FZR, FZS, VX, VXR, VXS) and need a reliable, OEM-dimension replacement. It suits riders wanting a full-bank replacement set, boatyards doing scheduled maintenance, and DIY mechanics who follow manufacturer torque and gap specifications. If you prioritize correct fit, consistent spark behavior, and reduced ignition noise for marine engines, this NGK V-Power kit offers a direct-swap solution.