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Marine & Outboard Spark Plugs

NGK Nickel Spark Plug DPR6EA-9 (5531)

SKU: GB-DPR6EA-9

$8.80
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The NGK DPR6EA-9 (Stock No. 5531) is a projected-tip resistor spark plug widely used in selected Honda four-stroke outboard motors. Featuring a nickel centre electrode, copper-core construction and built-in resistor, it provides dependable ignition, efficient heat transfer and reduced electrical interference. Its 12 mm thread, 19 mm reach and 0.9 mm factory gap suit marine engines specifically specifying DPR6EA-9.

Key benefits

Key Benefits

  • - Standard NGK resistor spark plug
  • - Widely used in Honda four-stroke outboards
  • - Projected-tip electrode
  • - Copper-core construction for efficient heat transfer
  • - Nickel centre and ground electrodes
  • - Built-in resistor for electrical-noise suppression
  • - Factory 0.9 mm / 0.035" gap
  • - NGK heat range 6
  • - Long 19 mm / ¾" reach
  • - Flat gasket seat

Specifications & Dimensions

  • - Brand: NGK
  • - Part Number: DPR6EA-9
  • - NGK Stock Number: 5531
  • - Spark Plug Type: Standard projected resistor
  • - Thread Diameter: 12 mm / 0.472"
  • - Thread Size: M12 × 1.25
  • - Thread Pitch: 1.25 mm / 0.049"
  • - Thread Reach: 19 mm / 0.750"
  • - Hex / Spanner Size: 18 mm / 0.709"
  • - Factory Spark Gap: 0.9 mm / 0.035"
  • - NGK Heat Range: 6
  • - Seat Type: Flat / gasket
  • - Resistor: Yes
  • - Centre Electrode: Nickel
  • - Centre Electrode Core: Copper
  • - Centre Electrode Type: Projected
  • - Ground Electrode: Nickel
  • - Ground Electrodes: 1
  • - Sealing Washer: Yes

Compatible Outboard Motors

  • Honda Outboards
  • DPR6EA-9 is extensively used across older and selected later Honda four-stroke outboard families. Model year and serial number should still be checked because Honda changed plug specifications during some production runs.
  • - Honda BF5 – 5 HP
  • - Honda BF7.5 – 7.5 HP
  • - Honda BF8 – 8 HP
  • - Honda BF9.9 – 9.9 HP
  • - Honda BF10 – 10 HP
  • - Honda BF15 – 15 HP
  • - Honda BF20 – 20 HP
  • - Honda BF25 – 25 HP
  • - Honda BF30 – 30 HP
  • - Honda BF35 – 35 HP
  • - Honda BF40 – 40 HP
  • - Honda BF45 – 45 HP
  • - Honda BF50 – 50 HP

Honda BF5

  • Selected earlier BF5 four-stroke engines use DPR6EA-9.
  • Later BF5 generations may specify different plugs, so check the complete model designation.

Honda BF7.5 / BF8 / BF9.9 / BF10

  • - BF7.5
  • - BF8A
  • - BF8B
  • - BF9.9A
  • - BF9.9B
  • - BF10A
  • - BF10B
  • These long-running Honda families have undergone multiple engine revisions, so not every engine carrying the same horsepower designation uses DPR6EA-9.

Honda BF15 / BF20

  • - BF15A
  • - BF15D
  • - BF20D
  • Depending on model generation, Honda may specify DPR5EA-9 or DPR6EA-9, making the engine identification important.

Honda BF25 / BF30

  • - Honda BF25A – 25 HP
  • - Honda BF30A – 30 HP
  • These three-cylinder four-stroke outboards commonly appear in marine application catalogues against DPR6EA-9.

Honda BF35 / BF40 / BF45 / BF50

  • - Honda BF35A – 35 HP
  • - Honda BF40A – 40 HP
  • - Honda BF45A – 45 HP
  • - Honda BF50A – 50 HP
  • Later BF40/BF50 generations may use different spark plugs, so model suffix and serial number should be checked before ordering.

Cross-Reference Spark Plugs & Part Numbers

  • - NGK: DPR6EA-9
  • - NGK Stock Number: 5531
  • - Honda: 98069-56916
  • - Honda: 98069-56926
  • - Champion: RA6HC

Important Fitment Information

  • The “-9” suffix denotes a nominal 0.9 mm factory electrode gap.
  • Do not confuse
  • - DPR5EA-9 – hotter NGK heat range 5
  • - DPR6EA-9 – NGK heat range 6
  • - DPR7EA-9 – colder NGK heat range 7
  • - DPR6EB-9 – different electrode/application specification
  • - DPR6EIX-9 – Iridium IX version for compatible applications
  • - DR6HS – short 12.7 mm reach and different electrode configuration
  • Although several plugs use the same M12 × 1.25 thread, their heat range, reach and electrode configuration can differ substantially.

Signs the Spark Plug Needs Replacing

  • - Difficult starting
  • - Rough or unstable idle
  • - Engine misfire
  • - Hesitation during acceleration
  • - Reduced engine power
  • - Increased fuel consumption
  • - Carbon deposits
  • - Fuel or oil fouling
  • - Excessive electrode wear
  • - Corrosion
  • - Cracked ceramic insulator

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