The NGK LFR6A-11 (Stock No. 3672) is a long-reach resistor spark plug used in a broad range of Yamaha four-stroke outboards and selected other marine engines. Its projected nickel centre electrode, copper-core construction and 26.5 mm thread reach provide dependable ignition and efficient heat transfer. With an M14 × 1.25 thread, 16 mm hex, NGK heat range 6 and 1.1 mm gap, it is suited to many Yamaha F-series engines.
Marine & Outboard Spark Plugs
NGK V-Power Spark Plug LFR6A-11 (3672)
SKU: GB-LFR6A-11
$24.05
Key benefits
Key Benefits
- - NGK Stock Number: 3672
- - Nickel centre electrode with copper core
- - Projected firing-end design
- - Built-in resistor for electrical-noise suppression
- - Long 26.5 mm / 1.043" reach
- - M14 × 1.25 thread
- - 16 mm / 5/8" hex
- - 1.1 mm / 0.043" gap
- - NGK heat range 6
- - Flat/gasket seat
- - Excellent heat transfer
- - Reliable ignition under marine operating conditions
- - Widely used in Yamaha four-stroke outboards
- - Iridium upgrade available for many applications: LFR6AIX-11
Specifications & Dimensions
- - Brand: NGK
- - Part Number: LFR6A-11
- - NGK Stock Number: 3672
- - Spark Plug Type: Standard resistor
- - Thread Diameter: 14 mm / 0.551"
- - Thread: M14 × 1.25
- - Thread Reach: 26.5 mm / 1.043"
- - Hex / Spanner Size: 16 mm / 5/8"
- - Spark Gap: 1.1 mm / 0.043"
- - NGK Heat Range: 6
- - Seat Type: Flat / gasket
- - Resistor: Yes
- - Centre Electrode: Nickel
- - Centre Electrode Core: Copper
- - Electrode Projection: Projected
- - Ground Electrodes: 1
- - Terminal: Solid
- - Sealing Washer: Yes
Compatible Outboard Motors
- Yamaha 115 HP Four-Stroke
- - Yamaha F115
- - Yamaha F115A
- - Yamaha F115B
- - Yamaha F115TLR
- - Yamaha F115TXR
- - Yamaha LF115
- - Yamaha LF115TXR
- These applications are typically 4-cylinder four-stroke engines requiring 4 spark plugs for a complete replacement set.
Yamaha 150 HP Four-Stroke
- - Yamaha F150
- - Yamaha F150A
- - Yamaha F150B
- - Yamaha F150D
- - Yamaha F150LA
- - Yamaha F150XA
- - Yamaha LF150
- - Yamaha LF150XA
Yamaha 200 HP Four-Stroke
- - Yamaha F200
- - Yamaha F200A
- - Yamaha F200B
- - Yamaha F200C
- - Yamaha LF200
- - Selected F200/LF200 model suffixes and production years
Yamaha 225 HP Four-Stroke
- - Yamaha F225
- - Yamaha F225A
- - Yamaha F225B
- - Yamaha F225C
- - Yamaha LF225
- - Selected F225/LF225 TXR, TUR and related variants
- Many F225 applications specify LFR6A-11, although some earlier/related 225 HP models specify LFR5A-11. Model suffix and production year therefore matter.
Yamaha 250 HP Four-Stroke
- - Yamaha F250
- - Yamaha F250A
- - Yamaha F250B
- - Yamaha LF250
- - Selected F250/LF250 model variants
- Again, not every Yamaha F250 uses LFR6A-11. Some model/year combinations use LFR5A-11 or another plug specification.
Yamaha 300 HP Four-Stroke
- LFR6A-11 is also specified for selected Yamaha F300-series four-stroke applications.
Cross-Reference / Related Part Numbers
- - NGK: LFR6A-11
- - NGK Stock No.: 3672
- - NGK Iridium alternative: LFR6AIX-11
- - NGK Iridium Stock No.: 6619
- - Yamaha: 94702-00427
- - Yamaha: 94702-00426 – associated/superseded application reference on selected engines
- - Yamaha: 94709-00427 – market/application dependent
- For Yamaha parts, the exact service number should be confirmed against the engine model and serial/production identification before ordering.
Yamaha Fitment Warning
- Yamaha has used different spark plugs within the same horsepower rating as engine designs and production generations changed. For example, F200, F225 and F250 model families can have different spark-plug specifications depending on the exact model suffix, production year and engine family.
Signs the Spark Plug Needs Replacing
- - Difficult starting
- - Rough idle
- - Engine misfire
- - Hesitation during acceleration
- - Reduced engine power
- - Poor high-RPM operation
- - Increased fuel consumption
- - Carbon fouling
- - Oil or fuel contamination
- - Excessive electrode wear
- - Enlarged electrode gap
- - Corrosion
- - Cracked ceramic insulator
- - Damaged sealing washer
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