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Marine & Outboard Spark Plugs

NGK V-Power Spark Plug LFR4A-E (6499)

SKU: GB-LFR4A-E

$23.95
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The NGK LFR4A-E (Stock No. 6499) is a V-Power resistor spark plug designed for selected Mercury 75, 80, 90, 100 and 115 HP EFI four-stroke outboards. Featuring a nickel centre electrode, copper core, projected firing end and corrosion-resistant metal plating, it provides reliable ignition and efficient heat transfer. Its long 26.5 mm reach, 14 mm thread and 0.8 mm gap suit specific Mercury 1.7L four-stroke engines.

Key benefits

Key Benefits

  • - NGK Stock Number: 6499
  • - V-Power spark plug design
  • - Nickel centre electrode
  • - Copper-core construction for efficient heat transfer
  • - Projected firing end
  • - Built-in resistor
  • - Special 10 kΩ resistor specification
  • - Trivalent metal plating for corrosion resistance
  • - 0.8 mm / 0.032" application gap
  • - NGK heat range 4
  • - Extra-long 26.5 mm / 1.043" thread reach
  • - Designed for selected Mercury EFI four-stroke outboards

Specifications & Dimensions

  • - Brand: NGK
  • - Part Number: LFR4A-E
  • - NGK Stock Number: 6499
  • - Type: V-Power / resistor
  • - Thread Diameter: 14 mm / 0.551"
  • - Thread Size: M14 × 1.25
  • - Thread Reach: 26.5 mm / 1.043"
  • - Hex / Spanner Size: 16 mm / 5/8"
  • - Application Spark Gap: 0.8 mm / 0.032"
  • - NGK Heat Range: 4
  • - Seat: Flat / gasket
  • - Resistor: Yes
  • - Resistance: approximately 10 kΩ
  • - Centre Electrode: Nickel
  • - Centre Electrode Core: Copper
  • - Electrode Configuration: Projected
  • - Terminal: Solid
  • - Sealing Washer: Yes

Compatible Outboard Motors

  • Mercury 75 HP FourStroke
  • - Mercury 75 HP EFI FourStroke
  • - 1.7L
  • - USA serial 1B366823–2B094995
  • - LFR4A-E
  • - 0.032" / 0.8 mm gap

Mercury 80 HP FourStroke

  • - Mercury 80 HP EFI FourStroke – 1.7L
  • - USA serial 1B366823–2B094995
  • - Belgian production serial 0P401000 onward within the applicable 1.7L generation
  • - LFR4A-E
  • - 0.8 mm / 0.032" gap

Mercury 90 HP FourStroke

  • - Mercury 90 HP EFI FourStroke
  • - 1.7L
  • - USA serial 1B366823–2B094995
  • - LFR4A-E
  • - 0.8 mm / 0.032" gap

Mercury 100 HP FourStroke

  • - Mercury 100 HP EFI FourStroke
  • - 1.7L
  • - USA serial 1B366823–2B094995
  • - Belgian production within the corresponding 1.7L range
  • - LFR4A-E
  • - 0.8 mm / 0.032" gap

Mercury 115 HP FourStroke

  • - Mercury 115 HP EFI FourStroke
  • - 1.7L
  • - USA serial 1B366823–2B094995
  • - LFR4A-E
  • - 0.8 mm / 0.032" gap

Cross-Reference Part Numbers

  • - NGK: LFR4A-E
  • - NGK Stock No.: 6499
  • - Mercury: 33-898829001
  • - Mercury: 898829001
  • - Mercury / Quicksilver: 8M0157328
  • - Mercury: 33-8M0157328

Important Fitment Information

  • LFR4A-E has an unusually long 26.5 mm thread reach, so it should never be substituted simply because another spark plug shares its 14 mm thread diameter.
  • Important Mercury distinctions include
  • - 75 HP 1596 cc, serial 0G960500–1B366822 → LFR5A-11
  • - 75 HP 1.7L, serial 1B366823–2B094995 → LFR4A-E
  • - 75 HP 2.1L, serial 2B094996 onward → ZFR5F
  • - 90 HP 1596 cc, serial 0G960500–1B366822 → LFR5A-11
  • - 90 HP 1.7L, serial 1B366823–2B094995 → LFR4A-E
  • - 115 HP EFI 1.7L through serial 1B366822 → LFR6A-11
  • - 115 HP EFI 1.7L, serial 1B366823–2B094995 → LFR4A-E Marine Engine
  • This makes engine displacement and serial number essential when determining compatibility.

Signs the Spark Plug Needs Replacing

  • - Difficult starting
  • - Rough or unstable idle
  • - Engine misfire
  • - Hesitation during acceleration
  • - Reduced engine power
  • - Poor high-RPM performance
  • - Increased fuel consumption
  • - Carbon or fuel deposits
  • - Worn centre or ground electrode
  • - Corrosion
  • - Cracked ceramic insulator
  • - Damaged sealing washer

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