NGK Spark Plug LFR6A 4-Pack for Watercraft — 26.5mm Reach, V-Power V-Cut, 16mm Hex

NGK LFR6A 6668 is a genuine 4-pack V-Power spark plug set designed to restore reliable ignition in compatible watercraft engines.

This set contains four brand-new NGK V-Power LFR6A (part 6668) spark plugs built with a 26.5mm reach, 16mm hex, 0.9mm electrode gap and a 5 kΩ internal resistor. The plugs use NGK’s V-Power v-cut center electrode to help the spark form at the electrode edge, which improves ignitability and reduces quenching in small-displacement marine engines. These plugs are offered as a direct-fit replacement for a range of Yamaha-style watercraft models including FX, FZR, FZS, VX, VXR and VXS where LFR6A is specified.

Which watercraft will these plugs fit?

These NGK LFR6A plugs match the common specifications for many Yamaha and similar watercraft engines that call for a 26.5mm reach and 16mm hex. Always check the owner’s manual or the OEM service data to confirm fitment before purchasing.

• Compatible models: FX, FZR, FZS, VX, VXR, VXS (when LFR6A is specified)
• Physical specs: 26.5mm reach, 16mm hex size for standard wrench fit
• Electrical specs: 0.9mm gap, 5 kΩ resistor built in

How does the V-Power v-cut design affect ignition?

The V-Power v-cut centers the spark toward the electrode edge which encourages faster spark development and reduces quenching near the electrode surfaces. That helps with initial ignitability under a range of engine conditions without changing engine tuning.

• Directs spark to electrode edge for quicker flame kernel formation
• Reduces quenching that can slow ignition in small chambers
• Maintains stable spark performance across load changes

What are the key installation and maintenance points?

Install these plugs to the manufacturer’s torque spec and confirm the 0.9mm gap before fitting. Replace in sets for multi-cylinder engines and inspect for fouling, electrode wear or deposits during routine maintenance.

• Check and set gap to 0.9mm if needed before installation
• Torque to vehicle OEM specification using a 16mm socket on the hex
• Replace all cylinders in the same service interval for consistent performance

Why choose NGK LFR6A over generic plugs?

NGK is a widely trusted OE supplier; the LFR6A uses a resistor to suppress interference, a proven v-cut electrode geometry, and materials matched for marine environments. Choosing genuine NGK ensures the part matches factory specs for fit and electrical behavior.

• Genuine NGK manufacturing and quality control
• Built-in 5 kΩ resistor to limit electromagnetic interference
• Designed for consistent fitment and reliable ignition in specified watercraft

Who is this for: This four-pack of NGK LFR6A 6668 plugs is aimed at watercraft owners and mechanics who need OEM-spec replacement spark plugs for compatible Yamaha-style models. It’s appropriate for routine maintenance, tune-ups, or part restoration when the vehicle manual specifies an LFR6A-type plug with a 26.5mm reach and 0.9mm gap. If you value consistent ignition performance from a recognized OE supplier, this NGK set is a direct, ready-to-install option.