7 Best Spark Plugs For Harley Davidson (Review) in 2021

Best Spark Plugs For Harley Davidson

There’s nothing complicated about spark plugs. However, despite them being small, a spark plug must always possess certain accuracy and durability. Generally, spark plugs can ride out extreme heat, vibrations, and electric currents. For a motorcycle to have an optimized engine performance right as it kickstarts, it must have a good spark plug. Harley Davidson motorcycles aren’t strangers to that. In fact, its iconic sound and top notch performance relies on having a good spark plug.

To find the best spark plug to match your Harley, we pulled together a list of the best in the market. Let’s break down the features of these spark plugs and learn why they’re the best for your Harley Davidson motorcycle.

What Are Spark Plugs For Harley-Davidson’s?

There’s a specific sound that only Harley Davidson motorcycles can emit especially upon kickstart. To get that perfect Harley sound and a brilliant combustion engine performance, the spark plug is the answer. Yes, we’re talking about those little devices that screw into the motorcycle engine. Spark plugs send electric currents from the ignition system toward the combustion chamber.

While it’s a common part for a motorcycle to have, your Harley works best with the right spark plug. To find the most suitable spark plug for your motorcycle, it’s best to consider its material. Not only should it be hard but it should also have high melting temperatures. The sharpest points on the plugs also play a role in picking the right spark plug. Make sure that it remains sharp for as long as possible. Finally, to make sure your spark plug is efficient, consider the size of the center of its electrode. Remember: smaller centers equals less voltage needed for it to spark.

1. NGK Iridium IX DCPR7EIX

One of the most efficient spark plugs on our list, the NGK Iridium IX DCPR7EIX features an electrode 25% smaller than platinum plugs. That’s only a quarter of the size of a typical nickel electrode. Its small diameter reduces its voltage requirement. In turn, this extends the life of the ignition system. Not only will your bike start faster but it will also last longer without undergoing extensive maintenance. If you’re looking for ways to make your Harley-Davidson faster, start off by giving it this plug.

Although more expensive due its iridium tips, these pre-gapped plugs come with enhanced metal shell plating. This provides the plugs improved anti corrosion features. As a downside, these plugs  have high reactivity. Using it on carbureted bikes fuels the plugs up too easily. NGK Iridium IX DCPR7EIX spark plugs work best on Harley Davidson Twin Cam engines.

2. E3 Powersports Spark Plug

The E3 Powersports Spark Plug works perfect if you’re looking for smooth acceleration and less carbon emission. A lot of motorcyclists use this making it one of the most popular today. This choice of spark plug is far more sustainable than others on the list.

This nickel-plated spark plug features the company’s proprietary DiamondFIRE ground electrode module. This makes fuel burning more efficient. Given that, the pressure inside the cylinder increases. The DiamondFIRE ground electrode extends the plug so it’s projected right into the combustion chamber. It brings the plug closer to the air and fuel mixture therefore allowing the fuel to spark quicker with more efficiency. 

Even with a variety of sizes, these spark plugs don’t perfectly match motorcycles with large gaps. Therefore, they work best with most Harley-Davidson motorcycles. 

3. ACDelco 41-993 Professional Iridium Spark Plug 

Iridium spark plugs might be more expensive but they prove to be more dynamic than others. The ACDelco 41-993 Professional Iridium Spark Plug is one of the best especially for Harley-Davidson motorcycles. ACDelco specifically manufactured these plugs for improved engine idle stability as well as smoother performance. With the plugs’ iridium fine-wire electrodes, you’ll be able to experience refined cold starting and swift acceleration.

Not to mention, the presence of iridium improves a motorcycle’s fuel usage by enhancing fuel ignition. It also burns off carbon deposits more quickly versus other plugs. Moreover, with its one-piece suppressor seal, any radio frequencies that affect the electronics of your bike get constrained. This spark plug perfectly suits either a Harley-Davidson Twin Cam or Sportster.

4. Denso PK20TT Platinum Spark Plug

The design of the Denso PK20TT Platinum TT Spark Plug proves unique versus other spark plugs. The patented design of these platinum plugs features a twin-tip design. This specifically improves the ignition, therefore, extending its shelf-life and reliability. Before Denso patented this tech, only high-tech automobiles possessed twin-tip designs.

This spark plug features a platinum center electrode with a titanium-enhanced alloy around it. Most platinum plugs only have platinum-only center electrodes. However, to optimize its durability and minimize the tip erosion, Denso employs the use of titanium-enhanced alloys. In turn, Denso platinum plugs can go more than 60,000 miles with its peak spark performance.

Now, what does the second tip do? The secondary tip helps by lessening the interference of spark growth all while keeping the same gap. If you’re looking to promote your bike’s fuel economy and acceleration while minimizing engine misfires, these plugs are for you. They work perfectly with Harley-Davidson Sporster or Twin Cam bikes.

5. Tuning Store Iridium Spark Plug

Just like the other iridium plugs on our list, the Tuning Store Iridium Spark Plug comes with iridium electrodes. This increases the overall performance of the bike and extends the life of the plug as well as the bike. It’s an efficient choice for those who are looking for quality more than just an affordable replacement plug.

Nickel and platinum electrodes require more voltage than iridium electrodes. Because iridium centers are smaller, it uses less voltage to create spark. The only drawback of this spark plug in particular is its gapping. Once installed, it may need to be reset. More than that, aside from it being pricier than platinum or copper spark plugs, it remains a smart choice. They also fit Harley-Davidson Twin Cam engines from 1999 to 2017 perfectly.

6. Screamin’ Eagle Performance Spark Plug

Many professionals and hobbyists would also refer you to a double platinum spark plug, particularly the Screamin’ Eagle Performance Spark Plug. The double platinum coating improves the plug’s erosion resistance therefore extending its life. Moreover, it features a V-trimmed ground electrode with a fine wire at the center. It enhances ignitability and startups while suppressing noise. Not to mention, it minimizes interference with electronic devices.

The brand’s proprietary Ribbed Core Technology also minimizes carbon fouling. This works great in racing applications which requires rich air/fuel conditions.

7. Champion Spark Plug RA8HC

For the past century, Champion Motors has proven itself a major player in spark plug development. This is the very company behind the first-ever commercial spark plug launched over a hundred years ago. The Champion Spark Plug RA8HC works particularly for Harley-Davidson Street Glide Special FLHXS 2014-2016 models.

Compared to the others on our list, it may be the most affordable. With a copper core, the spark plug uses nickel alloy electrodes as well as thermal bonding. In effect, it provides a wider insulator base with a long insulator nose. Moreover, at an 8-heat range rating, it truly is one of the most efficient in the market to prevent your motorcycle from overheating.

Since it’s a bespoke spark plug, it only works and perfectly suits any Harley-Davidson Street Glide Special FLHXS from 2014 to 2016. There’s no other spark plug that would better work with this motorcycle.

3 Types of Motorcycle Spark Plugs

With that said, 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. This remains the standard form that you’ll see on the market, unsurprisingly so since copper is one of the best electricity conductors. To prove this, copper spark plugs don’t easily overheat which makes it last longer. Copper plugs also remain an inexpensive choice. So, for those working under a budget, this could be the right choice for you. You can go as far as 40,000 miles before copper plugs show any sign of disintegration.

2. Platinum Spark Plugs

Platinum spark plugs, for obvious reasons, prove to be more expensive than copper plugs. Right now, there are two types of platinum plugs you’ll find in the market.

Firstly, single platinum spark plugs — less conductive than copper but more expensive. Why? It’s because platinum-tipped plugs last longer. Platinum naturally doesn’t wear out as fast as copper does. Overheating, perhaps, is the biggest issue among these plugs but they can go as far as 100,000 miles.

Double platinum spark plugs, on the other hand, provide better endurance. Due to it having double plates of platinum on the tip, it lasts up to twice as long as single platinum plugs. With that said, they’re also more expensive. Overheating also remains a persistent issue on these plugs.

3. Iridium Spark Plugs

The logic on why iridium-tipped spark plugs are the most expensive of all choices rely solely on its rarity. Generally, iridium is hard to find. It’s also not as great of a conductor as copper. However, iridium spark plugs remain a reliable choice. It can go as far as 60,000 miles without showing any sign of erosion.

Best Spark Plug Brands for Harley Davidson

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 yet remains to be the ACDelco Professional Iridium Spark Plug.

2. Denso

Denso doesn’t only dominate the Japanese market but also the rest of the world. The company manufactures automotive components independently. They also provide equipment for brands like Ford, Honda, Toyota, Benz, and Volvo. As aforementioned on our list, the Denso Platinum TT Spark Plug is only one of the best you’ll find on the market. The Denso Iridium Long Life Spark Plugs are also worth checking out!

3. E3 Spark Plugs

The unique selling point of E3 Spark Plugs relies on its sustainability. Compared to other companies, E3’s manufactures environmental-friendly spark plugs. In exchange, it provides cleaner fuel burn, thus, less carbon emission. The brand doesn’t only make motorcycle spark plugs but also produces plugs for cars, trucks, ATVs, and even lawnmowers. We recommend the E3 Spark Plug Powersports for your Harley Davidson motorcycle!

4. NGK

One of the most trusted original equipment manufacturers, Japan-based NGK company has a long history of excellence. The company also creates aftermarket accessories in the automotive industry as well as the aviation field. Aside from spark plugs, the company makes excelled oxygen sensors and ignition coils. The NGK Iridium IX Spark Plugs is one of the most sought-after in the market today.

Spark Plug Gapping

Gapping is not at all a complicated task. In fact, all you need a typical spark plug gap tool. However, remember that expanding or reducing gaps can be quite tricky. Don’t exert force on other parts of the plugs except the ground electrode strap. Don’t exercise force on the center electrode ceramic insulator or spark plug center electrode.

If you’re not sure how to gap a spark plug, your best bet would be pre-set spark plugs. Many manufacturers make this available online and in stores. 

How Often Should You Change Spark Plugs

To make sure that you won’t have any problems starting up your bike, it’s best to change spark plugs every 15,000 miles. However, if permitted, you can wait until 30,000 miles before changing it.

Make it a habit to check your spark plugs just as much as you check turn signals, tires, or brakes. If you’re buying a second-hand Harley, do ask when the last time the previous owner changed the spark plug. That way, you’ll know when to change it. 

Frequently Asked Questions

Q: Can I change spark plugs myself?

Of course! If you’re looking into saving money in the future, it’s a great skill to learn. Not to mention, it’s not very difficult. Acquiring this skill will make changing more efficient therefore keeping your bike in check. 

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, then you’re in for long rides and smooth performance. It’s the hardest of all materials. However, it’s expensive because it’s difficult to find. In the end, its durability is the very reason many people 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 improves due to its ultra-fine center electrode. This promotes faster combustion. Lastly, having iridium spark plugs results in improved fuel economy, making sure that gasoline burns efficiently. 

Final Thoughts

Spark plugs can make or break your whole motorcycle experience. They can either improve or demote the overall performance of your motorcycle. So, make sure you have the right spark plug to keep yourself from having troubles soon as you start your bike. To keep yourself from making a mistake, research about plugs and their benefits as well as compatibility. Consider its material and spark plug gaps as well. If you can’t measure the gap on your bike, take pre-gapped plugs for consideration for a hassle-free ride.