It’s all about the spark plug, those small, challenging critters that screw right into your engine and deliver the punches of electricity to ignite your fuel-air mix for that perfect burning engine performance and also sound connected with your Harley.

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Basically, spark plugs are basic devices, however highly accurate and made of materials that need to withstand excessive forces that heat, vibration, and electricity. They need to be solid enough to withstand years that abuse, and also elastic sufficient to withstand years of continuous vibration and jarring.

A great spark plug will certainly be built for endurance and also performance and also have high-grade steel tips come withstand continuous sparking. The materials must be built with compatible coefficients of expansion so that the warmth will not cause them to crack or rest apart.

As you have the right to now ascertain, the solid small plug is much much more than the seems.

Maintaining a plug is imperative, and also there are signs of wear and tear the will help you know what the difficulty is and also how to solve it. In the complying with list, I present to friend the significant issues associated with spark plugs. As soon as you encounter such an issue, you have to take into consideration cleaning or changing your plug.

Replacing spark plugs before their intended expiration is the best method to guarantee a safe and healthy ride for you and also your engine. If you want to constantly buy the best spark plug, check Michael Laurens course. Now, let’s take a look at a the list that was nicely made up by the civilization at, they also supplied 4 photos to present the illustration of the plug, take into account these space all plugs the have been in use for a year or over.

Spark Plug Gap

One of the tricks to success is making certain the space is correct, and also this is excellent by checking it v a typical spark plug void tool. When you need to increase or reduce the gap, remember that the force you must exert must only it is in on the spark plug floor electrode strap. Never ever apply any type of force ~ above the spark plug facility electrode or center electrode ceramic insulator. An additional rule is that you have to never change the gap much more than three times in the plugs lifetime, and also never an ext than .008″ in one of two people direction. One more rule come remember is the you never exceed .055″ past the manufacturer’s tolerance uneven this is already pre-set through the manufacturer.

cross recommendation chart – metric to traditional (mm to the inch)


List the Top-Rated Spark Plugs for Harley Davidson comparison Table:

Product product image NameYearModelMore Information
NGK Iridium IX DCPR7EIX Spark Plugs for 1999-2016 Harley Davidson Twin video camer (Pair)1999-2016Twin cam (Pair)More Information
ACDelco 41-993 experienced Iridium Spark Plug (Pack that 4)1995Twin Cam/SportsterMore Information
E3 Spark Plug E3.36 Powersports Spark Plug, fill of 12014-2016Street Glide distinct FLHXSMore Information
Champion Spark Plug RA8HC because that Harley-Davidson Street Glide distinct FLHXS 2014-20162014-2016Street Glide unique FLHXSMore Information
DENSO # 3297 Iridium long LIFE Spark Plugs - SK20R11-4 pcs NEW2007Twin Cam/SportsterMore Information

The finest Spark Plugs because that Harley Davidson reviews & Buyer’s Guide:

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The NGK plugs space made indigenous a fine wire center electrode that comes with a Copper Core and an Iridium Alloy tip. The nickel electrodes have actually an Extremely High melt Point and also come v a Trivalent metal Plating sealed in a Pure Alumina Silicate Ceramic Insulator through Corrugated Ribs.

These spark plugs provide extreme heat resistant properties, excellent electric insulation characteristics and also are draft to stand up to a the majority of vibration and also knocking.

The threads space 12mm in ~ a 1.25mm pitch, and also the chair is a gasket type. Thus, the version comes with a 5K Ohm resistor and has a reach of 19mm ¾”, the gap is .031″ (0.8mm). The terminal uses a removable nut, and the in its entirety height is rated together JIS.


This is a share make that fits plenty of applications, also so, check prior to you install any kind of spark plug, and make sure the gap is come manufacturer requirements prior to sealing the plug-in place.

2. ACDelco 41-993 professional Iridium Spark Plug (Pack that 4)

ACDelco is a agency that boasts countless years of endure in developing high-quality performance basic motors original tools parts. The ACDelco iridium spark plug is engineered to offer intensified engine idle stability and extra smoother performance. It functions iridium fine-wire electrodes that ensure improved cold starting and quicker acceleration. Again, iridium ensures improved ignition that the fuel and also burning turn off carbon deposits created on the pointer of the plug, for this reason improving fuel economy.

Recommendations ACDelco iridium spark plug is the ideal choice for performance devices such as Harley-Davidson many thanks to smoother performance. What’s more, that comes v a one-piece suppressor seal the inhibits any radio frequency the can impact vehicle electronics.

3. E3 Spark Plug E3.36 Powersports Spark Plug, fill of 1

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The E3.36 comes with 12mm, ¾” with the plug and also uses a gasket chair design. This model is offered in the more modern-day Harley Davidson bikes, and also as such, that is engineered especially for these applications.


This model comes with the patented DiamondFIRE floor electrode, this electrode uses to legs to attach to the shell, and this optimizes warm transfer, and provide added absorption of intense vibration.

This design comes through a 5K Ohm resistor and has a 5/8 hex. The electrode is a copper core nickel model, and also the space is rigid and also preset, therefore you can not (must not) adjust it.


This is a bespoke spark plug because that very specific applications, it deserve to only be provided on 2014-2016 Street Glide special FLHXS models, and also is the finest spark plug for them too.” width=”1349″ height=”488″ frameborder=”0″ allowfullscreen=”allowfullscreen”>

4. Champion Spark Plug RA8HC for Harley-Davidson Street Glide special FLHXS 2014-2016

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Champion motors is a leader in spark plug innovation and development. They space the original agency that created the first commercial spark plug means back end a century ago. This design is your bespoke spark plug model for all Harley-Davidson Street Glide distinct FLHXS 2014-2016 models.

This is a copper core spark plug that supplies nickel alloy electrodes and thermal bonding, to develop a broader insulator base, through a lengthy insulator nose. The seed is non-removable.

This spark plug comes through an 8-heat range rating and has a standard 12mm thread with a 5K Ohm resistor.


If you very own a Harley-Davidson Street Glide distinct FLHXS 2014-2016 model bike 보다 this is the plug because that you, and also you yes, really shouldn’t use any other model. This is a proven and good spark plug at a good price too.

5. DENSO # 3297 Iridium lengthy LIFE Spark Plugs – SK20R11-4 computers NEW

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DENSO Iridium spark plug is the an initial to use iridium ~ above spark plugs and it’s now becoming the many popular machine for modern high-tech engines. This company has work the 360-degree laser-welding process to create a performance spark plug that is durable. Featuring modern technology, this an equipment is engineered to offer unmatched functionality, reliability, and also fitment.

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Recommendations This is just one of the best and long-lasting spark plug in the market, thanks to its iridium electrodes. Through Iridium electrodes, the DENSO performance spark plug offers improved acceleration, enhanced fuel economy, and prevents engine misfires.

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