Best Spark Plugs For Harley Davidson (Im An Actual Mechanic)

Last Updated on August 20, 2023 by Chase Manhattan

Are you struggling to find the best spark plugs for your Harley Davidson? I’ve been in your shoes before, and after thorough research, I found that using the right ones can deliver a significant performance boost.

This article will guide you through the top picks in the market – each designed to improve efficiency and horsepower. Let’s fire up this journey to finding those game-changing spark plugs!

Chase Manhattan

Importance of Choosing the Right Spark Plugs for Harley Davidson

Choosing the right spark plugs for your Harley Davidson motorcycle is crucial. It’s not just about getting a plug that fits, but one that optimizes performance and efficiency. This involves understanding the importance of material type, correct specifications, ignition energy requirements and even how different brands might affect your biking experience.

Spark plug material matters tremendously when it comes to durability and heat resistance. Iridium spark plugs are ideal for Harley Davidson bikes due to their longevity and superior heat tolerance compared to with other materials like copper.

Platinum ones also fare well in terms of performance. Yet another aspect to consider is the energy requirement necessary for fuel ignition, which varies depending on specific engine needs.

The value of reputable brands cannot be understated either. For instance, NGK DCPR7EIX is a highly recommended iridium product known for its optimum delivery of ignition energy at just the right moments during combustion cycles.

Understanding your bike’s unique needs based on its model is paramount as different models may require distinct types of spark plugs.

A useful tool here would be the Harley Davidson Spark Plug Chart which provides valuable insights including correct specifications best suited for various models.

Keep in mind though; this quest towards optimal motorcycle function does come with cost considerations especially since iridium alternatives tend to command heftier price tags compared to copper or platinum counterparts – an investment worthwhile nonetheless considering longer-term benefits they offer such as enhanced power output alongside improved fuel economy.

NGK Iridium IX DCPR7EIX Spark Plugs
E3 Spark Plugs

CNPAPC Upgrade Double Iridium IX Spark Plugs
V-Twin Performance Spark Plugs
Denso PK20TT Spark Plugs

Quick Recommendations

For a quick recommendation, take a look at the product list or scroll down to find my detailed reviews.

Best Spark Plugs for Harley Davidson

In this section, I go into detail about each of my recommendations, why I’ve recommended them, and the benefits you’ll experience. However, if you’d like a more combined view, I’ll be leaving a comparison table below:

1. NGK Iridium IX DCPR7EIX Spark Plugs for 1999-2016 Harley Davidson Twin Cam

NGK Iridium IX DCPR7EIX Spark Plugs Product Image

Optimal performance for Harley Davidson Twin Cam motors.


  • NGK Iridium IX DCPR7EIX spark plugs are specifically designed for 1999 – 2016 Harley Davidson Twin Cam motorcycles.
  • They feature a metal top and nickel core material for durability and longevity.
  • The spark plugs are manufactured by NGK, a trusted brand in automotive replacement parts.
  • These spark plugs have received high ratings from customers, with an average rating of 4.7 out of 5 stars based on over 3,610 reviews.
  • The exterior of the spark plugs is painted for added protection and aesthetic appeal.
  • They come in compact packaging, with dimensions of 3.7 x 2.28 x 1.18 inches and weigh only 1.44 ounces.

As someone who values top-notch performance, I have found the NGK Iridium IX DCPR7EIX Spark Plugs for Harley Davidson Twin Cam to be an absolute game changer.

These spark plugs deliver exceptional power with an increase of up to 3 horsepower – a noticeable difference when you’re out on the road. The iridium electrode in these plugs is a marvel of technology; it’s 25% smaller than those of platinum ones and only 1/4 the size of conventional nickel electrodes. This feature reduces voltage requirement which prolongs ignition system life.

One standout characteristic that sets these NGK spark plugs apart from their competitors is their already pre-gapped design.

This offers convenience and lessens any installation worries about getting your gaps just right — a true godsend if you want to get back on the roads swiftly as I do!

Furthermore, they are engineered with enhanced anti-corrosion qualities due to its new metal shell plating, extending durability under harsh conditions.

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We selected this product as No. 1 because it impeccably merges innovation, longevity and practicality without compromising performance – all at competitive pricing unmatched by similar products in the market.

With NGK Iridium IX DCPR7EIX Spark Plugs installed in my Harley Davidson Twin Cam, every ride feels smooth and powerful; there’s no turning back once you’ve tasted such excellence!

This product is perfect for Harley Davidson owners with 1999-2016 Twin Cam motors looking to upgrade their spark plugs. Upgrade your motorcycle spark plugs today with NGK Iridium IX DCPR7EIX Spark Plugs!

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2. E3 Spark Plugs

E3 Spark Plugs Product Image

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Enhance Power and Efficiency for Powersport Engines.


  • Designed specifically for motorcycles
  • Alloy steel top material for durability and performance
  • Copper core material for enhanced conductivity
  • Gap size of 0.04 inches for optimal spark
  • Trusted brand: E3 Spark Plugs
  • Available since August 2008 with positive customer reviews

I’ve been using E3 Spark Plugs in my power sport vehicles for quite some time now, and I’m pleased to say they’ve never let me down.

These spark plugs are a significant upgrade from the standard ones available on the market. They truly live up to their claim of increasing engine power output by 6%-12% depending on the engine class.

The crux of this product’s success lies in its patented DiamondFire technology. A true game-changer, it efficiently burns fuel and reduces greenhouse gases emitted by your vehicle, contributing to both environmental conservation and cost-saving benefits through improved fuel efficiency that ranges from 4% to 13%.

Moreover, this advanced design ensures quick starts and almost eliminates carbon deposits that could hamper engine performance otherwise.

Selecting E3 Spark Plugs as No.2 on our list was not an easy decision considering their top-tier features—however, when compared side-by-side with our No.1 pick based on affordability vs performance ratio, the difference was marginal yet noticeable enough for discerning users who look at price-to-performance equation closely.

This E3 Spark Plug is ideal for those with a passion for performance who live to push the limits on their powersport engines. Get more out of your ride with this spark plug – try it today!

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3. CNPAPC Upgrade Double Iridium IX Spark Plugs

CNPAPC Upgraded Double Iridum IX Spark Plugs Product Image

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Enhance Performance and Efficiency with Double Iridium Spark Plugs


  • Double Iridium top material for improved ignition performance
  • Thread size of 12 for compatibility with a wide range of vehicles
  • Gap size of 0.8 millimeters ensures optimal spark plug performance
  • Core material made of high – quality Iridium for durability and longevity
  • Customer reviews rating the product at 4.1 out of 5 stars, indicating customer satisfaction
  • Suitable for use in cars, making it versatile and practical

The CNPAPC Upgrade Double Iridium IX Spark Plugs take performance and durability to the next level. With noticeable improvements in throttle response and better fuel economy efficiency, these plugs are a top choice for high-performance engines.

They feature double iridium alloy tips that not only ensure a consistently stable spark but also boast an extremely high melting point for extended life. As it’s compatible with several models including 1999-2016 Harley Davidson Twin Cam, XL Sportster 883/1200 (1986-present) and the Dyna Super Glide.

This pack comes with two pieces and guarantees quick after-sales service with a full year warranty, securing its position as number three on our list.

We appreciate how CNPAPC values customer satisfaction so highly – if there are any concerns or issues they’re more than ready to address them quickly.

Furthermore, users have reported lessened flameout incidences when using these spark plugs which contributes significantly to keeping the engine in good running condition whilst ensuring lower fuel consumption rates.

In conclusion, the CNPAPC Upgrade Double Iridium IX Spark Plugs provide an ideal blend of improved performance, increased longevity and excellent customer service all at a competitive price point.

Their superior design technology ensures their suitability for today’s high-tech powerful engines making them well worth considering for your next upgrade.

The CNPAPC Upgrade Double Iridium IX Spark Plugs are perfect for professional car drivers, motorcycle enthusiasts, and performance-minded individuals who want to take their engine’s power and efficiency to the next level. Don’t wait any longer – get your spark plugs today!

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4. V-Twin Performance Spark Plugs

V-Twin Performance Spark Plugs Product Image

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Enhance your Harley-Davidson with longer-lasting, powerful spark plugs.


  • Made of high – quality nickel material for durability and performance
  • Specifically designed for V – Twin engines, ensuring optimal spark and combustion
  • Available from February 2019, making it a newer option in the market
  • Positive customer reviews with an average rating of 3.8 out of 5 stars
  • Compact package dimensions of 11.81 x 4.8 x 1.1 inches for easy storage and shipping
  • Lightweight at only 3.84 ounces, minimizing added weight to the engine

The V-Twin Performance Spark Plugs are a fantastic enhancement for your Harley, designed to replace the Harley spark plug #6R12.

This product stands out because of its long-lasting copper core electrode, which ensures durability and consistent performance. The benefits of the nickel plated housing can’t be underrated either – it provides excellent resistance against wear and tear, adding longevity to these spark plugs.

Additionally, with a 95% pure alumina insulator and heat crimping process in place, you’re guaranteed an almost leak-free seal.

Moreover, compatibility isn’t an issue with the V-Twin Performance Spark Plugs. Whether you ride a FLT from 1999-2016 or FXST from 1999 onwards, FLST from 1999 onwards or FXD between 1999 and 2017 or even XL dating back as far as 1986 until present day – this performance spark plug fits seamlessly into your motorcycle’s engine system.

These features combined make this product trustworthy for improving ignition efficiency while simultaneously enhancing fuel economy.

In usage experience shared by riders using V-Twin Performance Spark Plugs on their Harleys, there has been notable improvement in acceleration response compared to standard factory-installed spark plugs. In summing up the review based on design choices affecting users positively and negatively; this product does well on all fronts such as performance enhancement with no reported drawbacks.

Overall therefore we can conclude that investing in these reliable V-twin spark plugs is undeniably beneficial for every passionate rider seeking efficient bike maintenance solutions.

This product is perfect for the classic Harley-Davidson enthusiast who wants an improved spark plug performance. Upgrade your vehicle with V-Twin performance spark plugs today and experience a smoother, more powerful ride!

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5. Denso (4504) PK20TT Spark Plugs

Denso PK20TT Spark Plugs Product Image

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High-performance spark plug for experienced DIYers and mechanics


  • Metal top material for durability
  • Core made of platinum for enhanced performance
  • Trusted and reliable brand – Denso
  • Available since July 8, 2011
  • Suitable for automotive spark plug replacement
  • Positive customer reviews with a rating of 4.4 out of 5 stars

Denso (4504) PK20TT Spark Plugs are a great investment for car enthusiasts seeking reliable performance and durability. These spark plugs come packed with innovative technology, enhancing both engine efficiency and fuel economy.

The Platinum TT Plug indicates that these platinum spark plugs utilize twin-tip technology where the double platinum coating delivers superior ignition ability, causing the fuel to burn more efficiently within the engine chamber.

Renowned for their optimized electrode designs, Denso spark plugs ensure fast start-ups even in severe weather conditions. Additionally, they play an integral role in reducing carbon emissions – a factor increasingly important to today’s eco-conscious driver.

With package dimensions of 10.9 H x 2.8 L x 8.9 W centimeters and weight of just 0.136 kilograms, you’ll find this pack of four easy to store or transport if need be.

In terms of lifespan, I found these Denso PK20TT Spark Plugs offered remarkable longevity compared to other brands on the market – a testament to their quality design and build materials which ultimately leads to cost savings over time due to reduced replacement frequency. Hence it is clear why many users have been highly praising these Denso Spark Plugs for their excellent value-for-money proposition.

This Denso (4504) PK20TT Spark Plug is the best spark plug suited for experienced diyers and automotive mechanics alike who are looking for a reliable, easy-to-install spark plug replacement. Install the Denso (4504) PK20TT Spark Plug now and get ready to experience improved performance in your engine!

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1. What are the best spark plugs for my Harley Davidson?

The best spark plugs for your Harley Davidson will depend on various factors such as the model and year of your bike, as well as your riding style and preferences. It is recommended to consult your owner’s manual or seek advice from a knowledgeable mechanic or Harley Davidson dealership to determine the most suitable spark plugs for your specific bike.

2. What are the benefits of iridium spark plugs for Harley Davidsons?

Iridium spark plugs offer improved ignition performance and efficient fuel combustion, resulting in enhanced throttle response and smoother engine operation for motorcycles. Their durability and extended service life make them a cost-effective choice, while the compatibility with various motorcycle models ensures easy access for riders seeking to optimize their engine’s performance and reliability.

3. How often should I change the spark plugs in my Harley Davidson?

It is generally recommended to change the spark plugs in your Harley Davidson every 10,000-12,000 miles or approximately once a year. However, it is important to check your owner’s manual for specific maintenance intervals as they can vary depending on the model and year of your bike.

4. What benefits does a high-performance spark plug offer for my Harley Davidson?

High-performance spark plugs can offer improved ignition efficiency, enhanced combustion processes, increased horsepower and torque output, smoother acceleration, and potential fuel efficiency gains. They are designed to withstand higher temperatures and provide reliable performance under demanding riding conditions.

5. Can I install high-performance spark plugs myself on my Harley Davidson?

While it is possible to install high-performance spark plugs yourself on your Harley Davidson if you have some mechanical knowledge and experience working with motorcycles, it is highly recommended to have them installed by a qualified mechanic or at a reputable service center. Proper installation ensures correct fitment and avoids any potential damage that may arise from improper installation techniques.

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