{"product_id":"lfr6a-spark-plug","title":"NGK LFR6A Spark Plug - 6668","description":"\u003cp\u003e\u003cimg src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0056\/9429\/2079\/files\/ngk_logo_1.png?v=1780608867\" alt=\"\"\u003e\u003c\/p\u003e\n\u003ch2\u003eNGK LFR6A Spark Plug – 6668\u003c\/h2\u003e\n\u003cp\u003eThe NGK LFR6A Spark Plug, stock number 6668, is a proven ignition replacement for select Yamaha four-stroke marine engines, including the popular 1.8L High Output powerplant used in Yamaha jet boats and WaveRunners. Designed for dependable spark delivery and efficient combustion, it helps maintain quick starting, smooth idle quality, responsive acceleration, and consistent performance throughout the RPM range.\u003c\/p\u003e\n\u003cp\u003eBuilt with a copper-core center electrode and durable nickel firing surfaces, the LFR6A transfers heat efficiently while providing reliable ignition under demanding marine operating conditions. Its resistor construction helps reduce electrical interference with onboard electronics, making it well suited for modern Yamaha engine management systems.\u003c\/p\u003e\n\u003cp\u003eWorn or fouled plugs can contribute to hard starting, hesitation, misfires, rough running, and loss of performance. Installing fresh NGK 6668 spark plugs during scheduled maintenance helps restore proper combustion and keeps your Yamaha marine engine performing as intended.\u003c\/p\u003e\n\u003ch3\u003eSpark Plug Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eManufacturer: NGK\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003ePart Number: LFR6A\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNGK Stock Number: 6668\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eType: Resistor spark plug\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eElectrode Core: Copper\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eCenter Electrode Material: Nickel\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eGround Electrode Material: Nickel\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eHeat Range: 6\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eThread Size: M14 x 1.25\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eThread Reach: 26.5 mm\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eHex Size: 16 mm \/ 5\/8\"\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSeat Type: Gasket\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003ePreset Gap: 0.9 mm \/ .036\"\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eApproximate Resistance: 5,000 ohms\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSold Individually\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCommon Yamaha Engine Applications\u003c\/h3\u003e\n\u003cp\u003eThe NGK LFR6A \/ 6668 is commonly used with Yamaha four-stroke marine engines, including:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 1.8L High Output\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 1812cc HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 1.8L Naturally Aspirated\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 1812cc Four-Cylinder\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSelect Yamaha 1.9L 1898cc High Output applications\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eBecause Yamaha has used both naturally aspirated and supercharged versions of its 1.8L engine, horsepower or displacement alone should not be used to determine spark plug compatibility.\u003c\/p\u003e\n\u003ch3\u003eYamaha Jet Boat Fitment\u003c\/h3\u003e\n\u003cp\u003eDepending on model year and installed engine package, the NGK LFR6A is commonly used in Yamaha boats such as:\u003c\/p\u003e\n\u003ch4\u003eYamaha 19-Foot Models\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha AR190\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha SX190\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 190 FSH\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 190 FSH Sport\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 190 FSH Deluxe\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eYamaha 21 \u0026amp; 22-Foot Models\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212X\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212S\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212SS\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212 Limited\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212 Limited S\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212SD\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212SE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212XE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 212XD\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSelect Yamaha 222 Series models\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch4\u003eYamaha 24 \u0026amp; 25-Foot Models\u003c\/h4\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha AR240 High Output\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha SX240 High Output\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 242 Limited\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 242 Limited S\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 242 Limited SE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 242X\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 242XE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha AR250\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha SX250\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 252S\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 252SE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 252XE\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 252 FSH Sport\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eYamaha WaveRunner Fitment\u003c\/h3\u003e\n\u003cp\u003eThe NGK 6668 is also commonly used in compatible Yamaha WaveRunner models, including:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha FX HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha FX Cruiser HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha FX Cruiser SHO – select applications\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha VXR\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha VXS\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha VX Cruiser HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha VX Limited HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha GP HO\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSelect Yamaha GP1800 applications\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eYamaha OEM Cross References\u003c\/h3\u003e\n\u003cp\u003eThe NGK LFR6A \/ 6668 is commonly associated with Yamaha replacement numbers including:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha LFR-6A000-00-00\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 94702-00427-00\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eYamaha 94709-00427\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNGK LFR6A\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNGK 6668\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eAlways compare the original plug or Yamaha engine specification before ordering.\u003c\/p\u003e\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cp\u003eGenuine NGK LFR6A spark plug\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eNGK stock number 6668\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003ePopular replacement for Yamaha 1.8L HO marine engines\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eCopper-core electrode provides efficient heat transfer\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eResistor construction helps suppress electronic interference\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSupports smooth starting and consistent acceleration\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eHelps maintain efficient combustion under varying engine loads\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eSuitable for Yamaha jet boats and WaveRunners\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003eIdeal for seasonal service and routine tune-ups\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDependable Ignition for Yamaha Marine Engines\u003c\/h3\u003e\n\u003cp\u003eYamaha's high-output marine engines spend much of their operating life under significant load, making proper ignition maintenance especially important. Electrode wear and combustion deposits can eventually reduce spark quality, resulting in harder starts, hesitation, or diminished performance. Replacing the plugs at the appropriate service interval helps maintain the smooth power delivery Yamaha engines are known for.\u003c\/p\u003e\n\u003cp\u003eWhether you're servicing an AR190, SX190, 190 FSH, 212X, AR240, SX240, 242 Limited, AR250, FX HO, VXR, or another compatible Yamaha marine application, the NGK LFR6A Spark Plug – 6668 provides proven NGK quality and reliable ignition performance.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFitment Note:\u003c\/strong\u003e Yamaha has used different spark plugs in naturally aspirated, HO, SHO, SVHO, and other engine configurations, even when displacement is similar. Do not determine compatibility by boat or WaveRunner model alone. Verify \u003cstrong\u003eNGK LFR6A \/ stock #6668\u003c\/strong\u003e against your Yamaha engine model, year, or original OEM spark plug number before ordering.\u003c\/p\u003e","brand":"Land 'N' Sea","offers":[{"title":"Default Title","offer_id":50254709293313,"sku":"41-6668","price":13.49,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0056\/9429\/2079\/files\/Screenshot2026-08-29082703.png?v=1788006433","url":"https:\/\/inboardpartshq.com\/products\/lfr6a-spark-plug","provider":"Inboard Parts HQ","version":"1.0","type":"link"}