7 Best Spark Plugs for Harley Davidson

Finding the best spark plugs for Harley Davidson motorcycles is key to maintaining smooth performance, reliable startups, and long engine life. Spark plugs may be small, but they must be accurate and durable to withstand extreme heat, vibrations, and electric currents. For optimal engine performance, especially in Harley Davidson bikes, having a quality spark plug is essential.

These components play a critical role in igniting the air-fuel mixture inside the engine’s combustion chamber, directly impacting the bike’s power, fuel efficiency, and overall smoothness. Because Harley Davidson engines are known for their unique design and performance demands, selecting spark plugs that meet these specific requirements ensures your motorcycle runs reliably and efficiently.

To help you find the best fit, we’ve compiled a list of top spark plugs designed specifically for Harley Davidson bikes, highlighting their key features and benefits. Whether you’re looking for enhanced durability, improved ignition technology, or better fuel economy, this guide will assist you in choosing the right spark plug to keep your Harley roaring on the road. Standard spark plug options are available for bikes that use standard plugs, providing a reliable and cost-effective choice for many riders.

What Are Spark Plugs For Harley-Davidsons?

There’s a distinctive sound unique to Harley Davidson motorcycles, achieved through the right spark plug that delivers electric currents to the combustion chamber. Choosing a plug with durable material, sharp points, and a small center electrode ensures optimal engine performance and efficiency. Many riders find that Harley plugs last longer when made with iridium or platinum electrodes, as they reduce voltage requirement and wear compared to a conventional nickel electrode. It’s also important for riders to be aware of Harley Davidson ignition coil symptoms to maintain their vehicle’s performance.

1. NGK Iridium IX DCPR7EIX

One of the most efficient spark plugs on our list, the NGK Iridium IX DCPR7EIX features a 25% smaller iridium electrode than platinum plugs, which significantly reduces voltage requirement and extends ignition system life. The enhanced metal shell plating adds an extra layer of protection against corrosion and heat, ensuring your bike starts faster and runs smoother.

Ideal for Harley Davidson Twin Cam engines, these pre-gapped plugs arrive in a box, ready to install. While slightly more expensive, many customers note in their reviews that they are worth the purchase for their reliability.

2. E3 Powersports Spark Plug

The E3 Powersports plug is popular among riders for smooth acceleration and reduced carbon emissions. Featuring a nickel-plated design and DiamondFIRE ground electrode, it boosts combustion efficiency and throttle response.

This plug fits most Harley Davidson models, though conditions such as larger gap size may require adjustment. It’s a great item for riders looking for performance upgrades, with solid stock availability and positive reviews.

3. ACDelco 41-993 Professional Iridium Spark Plug

The ACDelco 41-993, from an industry leader in auto parts, is designed for Harley Davidson Twin Cam and Sportster models. With a fine-wire iridium electrode, it improves starts, acceleration, and efficiency. Its one-piece suppressor seal reduces interference, while the metal shell plating provides corrosion resistance.

Though pricier, this plug extends ignition system life and is a smart purchase for riders who want long-term reliability. Often sold in sets, ACDelco plugs are backed by strong brand trust, promotions, and easy order options.

4. Denso PK20TT Platinum Spark Plug

The Denso PK20TT Platinum TT Spark Plug stands out with its twin-tip design, combining a platinum electrode with a titanium-enhanced alloy tip. This minimizes erosion and maintains consistent sparks. Riders appreciate its long life span, often exceeding 60,000 miles.

Well-suited for Harley Davidson Twin Cam and Sportster models, Denso plugs are frequently offered with seasonal discounts and are a reliable gift choice for Harley enthusiasts. Many customers report that the Denso plug is a performance upgrade worth every payment.

5. Tuning Store Iridium Spark Plug

Like the other iridium plugs on our list, the Tuning Store Iridium Spark Plug uses an advanced iridium electrode to enhance bike performance. It fits Harley Davidson Twin Cam engines from 1999–2017 and balances efficiency with longevity.

Often shown in online promotions, this plug is typically sold individually or in a set, making it easy to match your exact locale or date of delivery.

6. Screamin’ Eagle Performance Spark Plug

Many professionals and hobbyists recommend the Screamin’ Eagle Performance Spark Plug. It is designed with double-platinum coating, offers durability and ignition improvements. Its V-trimmed electrode improves startup reliability while reducing fouling.

Favored in racing conditions, this plug is perfect for riders seeking the ultimate performance upgrade. It’s widely available in Harley Davidson dealerships, often offered with seasonal promotions.

7. Champion Spark Plug RA8HC

Champion Motors has been a key player in spark plug development for over a century, introducing the first commercial spark plug. The Champion Spark Plug RA8HC is designed specifically for Harley-Davidson Street Glide Special FLHXS models from 2014 to 2016. It features a copper core with nickel alloy electrodes and thermal bonding, a wider insulator base, and a long insulator nose. With an 8-heat range rating, it effectively prevents overheating and offers an affordable, efficient option tailored to this specific Harley model.

3 Types of Motorcycle Spark Plugs

Let’s break down the types of spark plugs you may encounter on the market today.

1. Copper Spark Plugs

Most spark plugs feature copper tips because copper is an excellent conductor of electricity, making these plugs durable, inexpensive, and able to last up to 40,000 miles without significant wear. Copper spark plugs have ideal conductivity for igniting the bike’s combustion chamber, ensuring reliable performance in standard motorcycle engines.

2. Platinum Spark Plugs

Platinum spark plugs are more durable and longer-lasting than copper ones, with single platinum lasting up to 100,000 miles and double platinum offering even greater endurance, though both can be prone to overheating and are more expensive.

3. Iridium Spark Plugs

Iridium-tipped spark plugs are the most expensive due to the rarity of iridium, but they offer exceptional durability, lasting up to 60,000 miles without erosion.

Best Brands for Harley Davidson Spark Plugs

1. ACDelco

General Motors subsidiary, ACDelco, remains a big player in the automotive parts manufacturing industry. Headquartered in Grand Blanc, Mich, the company provides consumers with high-performance spark plugs. The brand’s best output remains the ACDelco Professional Iridium Spark Plug.

2. Denso

Denso is a global leader in automotive components, supplying top-quality spark plugs like the Denso Platinum TT and Iridium Long Life models for Harley Davidson motorcycles. Additionally, Denso single wire iridium spark plugs are available for Harley-Davidson models between 1999 and 2017, offering a durable and efficient option for these specific years.

3. E3 Spark Plugs

E3 Spark Plugs are environmentally friendly, providing cleaner fuel burn and less carbon emission, making the E3 Powersports model a great choice for your Harley Davidson motorcycle.

4. NGK

NGK, a trusted Japan-based manufacturer known for quality spark plugs, oxygen sensors, and ignition coils, produces the highly sought-after NGK Iridium IX Spark Plugs. Notably, NGK Iridium IX CR9EIX spark plugs can gain up to 3HP for 2017-newer Harley-Davidson M8 models, making them a performance-enhancing option for modern bikes.

Spark Plug Gapping

Gapping a spark plug is simple with a gap tool—just adjust the ground electrode strap carefully and avoid applying force to the center electrode or insulator; alternatively, opt for pre-set spark plugs for convenience.

How Often Should You Change Spark Plugs

Harley Davidson spark plugs typically need replacement every 15,000–30,000 miles, depending on riding conditions. If you buy a second-hand bike, always ask the last date the plugs were changed.

Regularly checking plugs is as important as checking tires, brakes, or rod bearings. If you notice misfires, it may be time for a change.

Frequently Asked Questions

Q: Can I change spark plugs myself?

Of Course! With the right tool set, you can safely return or change old plugs.

Q: Is Iridium the best material for spark plugs?

Iridium is the hardest material a spark plug can have. If you can get your hands on iridium plugs, you’re in for long rides and smooth performance. It’s the hardest of all materials. However, it’s expensive because it’s challenging to find. Ultimately, its durability is the very reason many prefer it over carbon or platinum.

Q: What are the benefits of having iridium spark plugs?

There are many reasons why iridium plugs sell out. Firstly, it improves acceleration. Right off the bat, you’d feel the difference between iridium and copper or platinum spark plugs. It also helps by giving your motorcycle more engine power. Climbing hills wouldn’t be a problem with this one. The starting characteristics of your engine also improve due to its ultra-fine center electrode. This promotes faster combustion. Lastly, having iridium spark plugs improves fuel economy, ensuring that gasoline burns efficiently.

Final Thoughts

Spark plugs can make or break your Harley Davidson riding experience. Whether you want standard copper, durable platinum, or the ultimate iridium option, the right plug ensures smoother performance and reliability.

Always check compatibility with your Harley Davidson model, look at reviews, and pay attention to information like plug gap, size, and warranty conditions. With the right choice, you’ll enjoy long-lasting performance and fewer issues down the road.