Best Spark Plugs For Harley Davidson Motorcycles

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In this article we’ll cover how to select the best spark plugs for your Harley Davidson.

How To Select The Right Spark Plugs For Your Harley Davidson

Refer to your owner’s manual and note the following details:

  • Designation of the spark plug (it can be Harley-Davidson 5R6A, 6R12, etc.)
  • Recommended plug gap.
  • Hexagon size, thread size (in mm), and length of thread (thread reach). If these details are not given in the owner’s manual, you may have to take out the spark plug and measure it using. Thread sizes in the USA can be 10, 12, 14, and 18 mm and the nut sizes vary accordingly. No. of threads or length of thread on the spark plug indicates the reach (how far it will go into the combustion chamber of the engine). The reach is important since this is the point of spark and ignition of the compressed gas.
  • The heat range of the spark plug: This is the measurement of how the spark plug can transfer the heat from the sparking area to the cooling system, and indicates the duration for which the spark plug can withstand the high temperature of combustion.
  • The material of the spark plug electrode, such as copper, silver, platinum, iridium, etc.

If you are looking for a Harley-Davidson spark plug, the designation is sufficient.

However, when you are looking for a good spark plug on online stores like Amazon, you should know and use the above details to select a suitable spark plug for your specific bike.

NGK Iridium IX DCPR7EIX Spark Plugs

  • Comes with a pre-gap setting.
  • NGK iridium electrode is 25% smaller than a platinum electrode spark plug and is 1/4th size of the nickel electrode.
  • A very small diameter center electrode reduces the requirement of voltage. The new plating on the shell has improved the anti-corrosion quality.

User reviews are good. Users used this spark plug for their 2000 Dyna Super Glide, 2009 Harley (cautioned to use proper tools for gap setting), and 2002 HD Heritage Softail. One user commented that this plug did not work on the Harley Electra Glide classic. User review suggests that you should not gap these plugs (please verify this before you purchase).

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NGK Iridium IX DCPR8EIX Spark Plugs

  • Comes with pre-gap setting
  • NGK iridium electrode is 25% smaller than a platinum electrode spark plug and is 1/4th size of the nickel electrode.
  • A very small diameter center electrode reduces the requirement of voltage.
  • The new plating on the shell has improved the anti-corrosion quality.

User reviews are positive.

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Harley Sportster Roadster XL 1200R (1986 to 2020) Iridium Performance Spark Plugs

  • Supreme performance with the highest level of technology.
  • Iridium electrode is smaller in diameter and requires less voltage and last longer compared to other spark plugs.
  • 12 mm thread diameter, 5/8ʺ hexagon, and 11/16ʺ thread reach.

User reviews are good.

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Iridium Performance Spark Plugs for Harley Softail Slim Twin Cam

  • Supreme performance with the highest level of technology.
  • Iridium electrode is smaller in diameter and requires less voltage and last longer compared to other spark plugs.
  • Item model no-OCP0231-AZ3
  • 12 mm thread diameter, 5/8ʺ Hex, and 11/16ʺ thread reach.

User reviews are normally good. Customers have used this on their 2006 Harley Ultra, 2011 Heritage Classic, and 2015 Road King.

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E3 Spark Plugs (E336)

  • Core material-copper. Top material- Alloy steel
  • Designed with colder heat ranges to enable modifications in performance and intense conditions.
  • Thread diameter-12 mm. Hexagon size-5/8ʺ. Reach-3/4ʺ
  • Engineered with a high nickel alloy center and ground electrode for extra life.
  • The presence of Yttrium-enhanced alloy helps reduce inside electrode temperature up to 8% for enhanced durability and less pre-ignition.

User reviews are good. Customers used this for their Harley models-2001 Electra Guide Ultra Classic, 2007 FLSTC, 2004 Screaming Eagle Electra Glide with the 103, 2006 Sportster 883 Low, 2004 Fat Boy, 2001 Sportster, Street Glide, and 1998 Electra Glide. One user wrote that this is a good replacement for HD 6R12 (model E3.36)

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Champion RA8HC for Harley Davidson Street Glide

A standard Champion brand spark plug features a wide insulator base for fast heat transfer, a copper core electrode for efficient conductivity.

NGK #6046 Iridium Spark Plugs

User reviews are good. Previous customers used this for their Harley model-Harley FLHTCU, and 2008 Ultra Classic.

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NGK Spark Plugs 2115 Iridium IX Spark Plug

No user reviews but NGK is a reputed brand.

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NGK Iridium Spark Plug BPR5EIX-11

  • Laser welded iridium center electrode tip.
  • Platinum disc welded to the rear side of the ground electrode for long life
  • Improved fuel economy, reduced emissions, faster start, and good acceleration.
  • Superior ignitability and long life.

No user reviews. NGK is a reliable and reputed brand.

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Harley Dyna Low Rider Performance Spark Plugs

  • Conventional spark plugs in OEM heat ranges.
  • Black ceramic body, the insulator is made from 95% pure alumina and has a strong resistance to heat shock.

User reviews are good. Customers used this for their Harley models-2005 Dyna Switchback, and 2001 XL 1200.

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NGK Iridium Spark Plug DCPR7EIX

NGK is a reliable brand. No user reviews.

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Champion RA8WHP (9701) Iridium Spark Plug

  • Core material-Iridium. Top metal-Metal.
  • This spark plug has a fine-wire iridium center electrode and platinum ground electrode for maximum performance.

User reviews are good. Customers used this for their Harley model-2013 HD Breakout (FXSB), 2017 HD Softail Slim FLSTC, and 2000 FLSTC.

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How many spark plugs are there in my Harley Davidson?

Normally Harley Davidson motorcycles have one spark plug in each cylinder, and so if your Harley has a V-Twin engine, there will be 2 spark plugs in total.

However, if your Harley has an M8 engine, then the number of spark plugs is two in each side, and hence total is 4 spark plugs.

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