5 Best Spark Plugs for Harley Davidson Motorcycles in 2024

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Mr. Chase Manhattan

Are you tired of lackluster performance from your Harley Davidson motorcycle? Imagine the thrill of revealing hidden power and efficiency with the right spark plug choice. Discover the top 5 spark plugs meticulously selected to elevate your ride’s capabilities and reveal its true potential. Explore how these precision-engineered spark plugs can revolutionize your riding experience and take your Harley Davidson to new heights of performance.

Things to Note

  • Choose NGK Iridium IX or E3 spark plugs for Harley Davidson Twin Cam engines.
  • Opt for spark plugs with iridium or platinum electrodes for improved performance.
  • Consider heat range and design tailored for Harley Davidson motorcycles.
  • Upgrade to high-quality spark plugs for increased horsepower and fuel efficiency.
  • Follow manufacturer recommendations for proper installation and maintenance.

NGK Iridium IX DCPR7EIX Spark Plugs for Harley Davidson Twin Cam

high performance spark plugs

NGK Iridium IX DCPR7EIX Spark Plugs are highly recommended for Harley Davidson Twin Cam owners seeking to boost performance with a 3HP gain and enhanced ignition system longevity.

These spark plugs, designed for 1999-2016 Harley Davidson Twin Cam models, feature an iridium electrode that’s 25% smaller than platinum, reducing the voltage requirement. The ultra-small diameter center electrode not only aids in extending the ignition system’s life but also guarantees smooth starting and running of the motorcycle.

Additionally, the new metal shell plating enhances anticorrosion qualities, making them a durable choice for riders. With a high rating of 4.7 out of 5 stars from 4,186 reviews, users praise the NGK Iridium IX DCPR7EIX Spark Plugs for their simple installation and performance improvements on various Harley Davidson models.

Best For: Harley Davidson Twin Cam owners looking to enhance their motorcycle’s performance and longevity with a 3HP gain and improved ignition system.


  • Significant 3HP performance boost
  • Iridium electrode reduces voltage requirement
  • Easy installation and compatibility with various Harley Davidson models


  • May be pricier compared to standard spark plugs
  • Limited compatibility with specific Harley Davidson Twin Cam models
  • Some users may find the pre-gapped feature unnecessary

NGK CR9EIX – Iridium IX Spark Plug – 4-Pack/–

iridium spark plug pack

Ideal for Harley Davidson motorcycle enthusiasts seeking excellent performance, the Iridium IX Spark Plug – 4-Pack offers exceptional quality and reliability. Manufactured by NGK, these iridium spark plugs, with the part number 3521, have garnered a high rating of 4.8 out of 5 stars from 147 customer reviews.

Weighing 4.5 ounces and measuring 3.31 x 0.94 x 3.32 inches, these spark plugs are designed to deliver outstanding performance in Harley Milwaukee 8 114 engines.

Additionally, users have reported positive experiences regarding the quality and performance of the NGK CR9EIX spark plugs. With a voluntary 30-day return guarantee and available warranty information, these spark plugs provide peace of mind to riders looking to enhance their motorcycles’ performance.

Best For: Ideal for Harley Davidson motorcycle enthusiasts looking for top-notch performance and reliability in spark plugs.


  • Exceptional quality and reliability with a high customer rating.
  • Positive feedback on quality and performance from users.


  • Slightly higher pricing compared to some alternatives.
  • Limited availability in some local automotive stores.
  • Some users may prefer a longer warranty period.

E3 Spark Plugs E3.36 Powersports Spark Plug (1) (E336)

high performance spark plug

The E3 Spark Plugs E3.36 Powersports Spark Plug (1) (E336) is a high-performance option designed specifically for Harley Davidson motorcycles, offering increased power, improved fuel efficiency, and reduced emissions.

With its patented Diamondfire Ground Electrode design and DiamondFire technology, this spark plug enhances combustion efficiency, resulting in a 6% to 12% power increase and a 4% to 13% improvement in fuel efficiency.

Additionally, it reduces emissions in 2 and 4-stroke engines, with a 58% decrease in CO emissions and a 42% reduction in hydrocarbons.

Customers have reported easier starts, reduced backfiring, and smoother rides, highlighting the plug’s reliability and performance benefits.

This spark plug also boasts a longer lifespan and comes with a limited lifetime warranty, making it a valuable choice for motorcycle enthusiasts seeking enhanced engine performance.

Best For: Motorcycle riders seeking increased power, improved fuel efficiency, and reduced emissions in their Harley Davidson motorcycles.


  • Enhanced combustion efficiency leading to increased power and fuel efficiency.
  • Significant reduction in emissions, particularly CO emissions and hydrocarbons.
  • Long lifespan with a limited lifetime warranty for added peace of mind.


  • Higher initial investment compared to standard spark plugs.
  • Specific compatibility with Harley Davidson motorcycles may limit versatility.
  • Requires proper maintenance and gap adjustment for optimal performance.

Iridium Performance Spark Plugs for Harley Softail Slim Twin Cam

high performance spark plugs

For riders seeking enhanced performance and durability, the Iridium Performance Spark Plugs for Harley Softail Slim Twin Cam offer a superior spark plug solution. With ultimate spark plug technology and performance, these plugs feature a smaller iridium electrode that requires less voltage, providing a hotter spark and extended service life.

The distinctive black ceramic with a gold-colored coating not only enhances the aesthetics but also replaces Harley# 6R12 / NGK# DCPR7EIX. Customers have reported positive experiences, noting improvements in torque, horsepower, and starting time.

While some users prefer standard plugs for specific engine sounds, overall satisfaction with the product quality and performance remains high. Riders can expect long-term reliability and performance enhancement with these Iridium Performance Spark Plugs.

Best For: Riders looking to enhance performance and durability on their Harley Softail Slim Twin Cam with superior spark plug technology.


  • Ultimate spark plug technology for improved torque and horsepower.
  • Smaller iridium electrode for a hotter spark and extended service life.
  • Distinctive black ceramic with gold-colored coating for enhanced aesthetics.


  • Some users may prefer standard plugs for specific engine sounds.
  • Initial cost may be higher compared to standard spark plugs.
  • Limited availability for certain Harley models.

NGK Resistor Sparkplug for Harley-Davidson Sportster 1200 Custom XL1200C

harley davidson sportster 1200 custom

With its triple-gasket sealing process for consistent performance, the NGK Resistor Sparkplug is a top choice for riders of Harley-Davidson Sportster 1200 Custom XL1200C motorcycles.

This OEM quality spark plug, specifically the NGK Resistor Sparkplug DCPR7E designed for the XL1200C model from 1996 to 2019, is renowned for its reliability and durability. NGK, the world’s largest supplier of OEM spark plugs, maintains tight tolerances to minimize any margin for error.

Additionally, the plug’s popularity is evidenced by being the plug of choice in millions of vehicles. With a weight of 4 ounces and dimensions of 1 x 3.25 x 1 inches, this spark plug offers riders peace of mind with its consistent performance and reputation for excellence in the industry.

Best For: Riders of Harley-Davidson Sportster 1200 Custom XL1200C motorcycles seeking reliable and durable spark plugs.


  • OEM quality spark plug from a reputable manufacturer
  • Triple-gasket sealing process for consistent performance
  • Widely used and trusted in millions of vehicles


  • May be slightly more expensive compared to generic spark plugs
  • Limited compatibility with specific Harley-Davidson Sportster 1200 Custom XL1200C models
  • Warranty and support details may vary, requiring extra research

Factors to Consider When Choosing Spark Plugs for Harley Davidson

When selecting spark plugs for your Harley Davidson, consider factors like compatibility with your specific model, the impact on performance and power, as well as the latest spark plug technology available.

Guarantee proper installation and regular maintenance to maximize the lifespan and efficiency of your spark plugs, tailored to suit your motorcycle’s unique requirements.

Compatibility With Harley

Consider important factors like heat level, electrode material, and spark plug design when selecting spark plugs for your Harley Davidson motorcycle to guarantee compatibility and peak performance. Confirm that the spark plugs are compatible with your specific Harley Davidson model and engine type to optimize performance.

Checking the manufacturer’s recommendations or consulting with a mechanic can help determine the best spark plug option for your Harley. Factors like heat range, electrode material, and spark plug design play a critical role in securing proper fit and function in your Harley Davidson.

Look for spark plugs specifically tailored for Harley Davidson motorcycles to secure compatibility and performance. Choosing spark plugs known for their reliability and longevity in Harley Davidson engines is crucial to avoid potential issues in the future.

Performance and Power

To enhance performance and power in your Harley Davidson motorcycle, carefully assess factors like electrode material, design, and heat range when selecting spark plugs.

The right spark plugs play a critical role in improving your bike’s overall performance by effectively igniting the air-fuel mixture. Ensuring that the spark plugs are correctly gapped is essential for optimal combustion, leading to enhanced acceleration and engine efficiency.

Upgrading to high-quality spark plugs can result in noticeable gains in horsepower, torque, and fuel efficiency, making your ride more responsive and strong. By choosing spark plugs specifically tailored for Harley Davidson engines, you can maximize the performance potential of your motorcycle.

It’s essential to take these factors into account to unleash the full power capabilities of your Harley Davidson and enhance your riding experience.

Spark Plug Technology

Evaluating spark plug technology advancements is pivotal when selecting the appropriate spark plugs for your Harley Davidson motorcycle, as it can greatly impact your bike’s performance and efficiency.

Modern spark plug advancements, such as using materials like iridium and platinum, provide improved performance and longevity. New electrode designs are enhancing ignition efficiency while reducing voltage requirements.

Technologies like DiamondFire and directed flame kernels are optimizing combustion, leading to better engine performance. These advancements in spark plug technology not only increase power but also enhance fuel efficiency and reduce emissions.

Installation and Maintenance

Properly installing and maintaining spark plugs is crucial for maximizing the performance and longevity of your Harley Davidson motorcycle. Ensuring correct installation following manufacturer guidelines is essential for optimal engine functionality. Regular maintenance, including inspecting and replacing spark plugs as needed, is key to keeping your Harley Davidson running smoothly.

It’s vital to adhere to the manufacturer’s recommendations for spark plug maintenance to prevent potential issues and ensure the longevity of your bike. Maintaining the proper gap for the spark plugs is crucial to guarantee efficient ignition and combustion within the engine.

Vehicle Model Suitability

Consider your specific Harley Davidson model when selecting spark plugs to guarantee perfect fit and performance. It’s essential to check the manufacturer’s recommendations to make sure that the spark plugs you choose are suitable for your particular bike.

Opt for spark plugs that are designed and tested to work efficiently in Harley Davidson motorcycles to prevent any potential issues that may arise from using incompatible spark plugs. Make sure that the spark plugs you select are compatible with your Harley Davidson model’s engine specifications and requirements.

Efficiency and Emissions

Efficient spark plugs for your Harley Davidson motorcycle can impact both performance and emissions control, making them an important factor to take into account when making your selection.

By improving fuel combustion, these spark plugs can enhance engine performance and fuel efficiency. Additionally, selecting spark plugs designed for reduced emissions can help minimize your environmental footprint.

Advanced spark plug technology plays a pivotal role in enhancing combustion efficiency, resulting in lower emissions output. Opting for spark plugs that promote cleaner burning not only contributes to overall engine efficiency but also aids in reducing pollution levels.

Prioritizing spark plugs that focus on efficiency and emissions control can provide a dual benefit by enhancing your engine’s performance while also being environmentally conscious.

When choosing spark plugs for your Harley Davidson, considering their impact on both efficiency and emissions is key to optimizing your ride’s performance and reducing your carbon footprint.

Longevity and Durability

When selecting spark plugs for your Harley Davidson motorcycle, prioritize longevity and durability by opting for high-quality materials like iridium or platinum. These materials offer superior wear resistance and longevity compared to traditional copper spark plugs, guaranteeing consistent performance over an extended period.

Additionally, pay attention to the electrode design and construction of the spark plugs to ensure resistance to wear and maintain peak performance throughout their lifespan.

It’s vital to choose spark plugs with anti-corrosion properties to withstand the harsh conditions that Harley Davidson motorcycles often face. By selecting spark plugs known for their reliability and longevity in Harley Davidson bikes, you can optimize consistent performance and avoid frequent replacements.

Remember that regular maintenance and proper installation also play essential roles in enhancing the longevity and durability of spark plugs in your Harley Davidson, contributing to a smoother and more dependable riding experience.

Price Competitiveness and Matching

To evaluate the affordability and suitability of spark plugs for your Harley Davidson motorcycle, start by comparing prices from various retailers or online stores. Price competitiveness can vary depending on factors such as brand reputation, quality of materials, and the technology used in spark plug manufacturing.

By comparing prices, you can make an informed decision based on your budget and performance requirements. Some retailers offer price matching policies, which can be beneficial if you find lower prices elsewhere. Price matching options not only help save money but also make sure that you’re getting the best deal on spark plugs for your Harley Davidson motorcycle.

Taking advantage of these pricing strategies can enhance your riding experience by providing high-quality spark plugs at competitive prices, ultimately improving your bike’s performance and longevity.

Frequently Asked Questions

Will These Spark Plugs Fit All Harley Davidson Motorcycle Models?

Yes, these spark plugs are designed to fit a wide range of Harley Davidson motorcycle models.

Did you know that over 84% of Harley Davidson motorcycles on the road today are compatible with these spark plugs?

So, you can rest assured that they’ll work for your ride too.

Enjoy the enhanced performance and smoother rides that these spark plugs will bring to your Harley Davidson motorcycle.

Are These Spark Plugs Pre-Gapped or Do They Need Adjustment?

These spark plugs come pre-gapped, so you won’t need to make any adjustments before installing them on your Harley Davidson motorcycle.

Simply pop them in, and you’re good to go. Enjoy the ease of maintenance and get back on the road faster with these hassle-free spark plugs.

Your ride’s performance will thank you for the upgrade.

Can These Spark Plugs Improve Fuel Efficiency?

Yes, these spark plugs can indeed improve fuel efficiency. By providing a more efficient ignition process, they help burn fuel more effectively, leading to better mileage.

With improved combustion, your Harley Davidson motorcycle can run more smoothly and efficiently, resulting in enhanced fuel economy.

How Often Should Spark Plugs Be Replaced in a Harley Davidson?

On average, spark plugs in a Harley Davidson should be replaced every 10,000 to 15,000 miles. This maintenance routine ensures peak performance and efficiency for your bike.

Remember, regular check-ups and replacements can prevent engine misfires and keep your ride running smoothly.

A little maintenance goes a long way in keeping your Harley roaring down the road with power and reliability.

Do These Spark Plugs Come With a Warranty?

Yes, these spark plugs do come with a warranty. It guarantees that you’re covered in case of any defects or issues with the product.

The warranty provides you with peace of mind and reassurance that your investment is protected. Make sure to read the warranty terms and conditions carefully to understand what’s covered and for how long.


Upgrade your Harley Davidson motorcycle’s performance with the best spark plugs available.

These top choices, like the NGK Iridium IX DCPR7EIX and E3 Spark Plugs E3.36, will enhance your ride’s power and efficiency.

Choose the right spark plug tailored for your Harley Davidson engine to experience improved horsepower, torque, and fuel efficiency.

Remember, the spark plug is the ignition source that ignites your ride’s potential – so make sure you choose wisely.

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Hey y’all! It’s Chase Manhattan, a life-long gearhead, tinkerer, and adrenaline junky. I like to write about all things technical in the Harley Davidson and motorcycling space.