Written By
Published Nov. 14, 2020

A critical part of any motorcycle, spark plugs are the essential component to the combustion of your fuel. This piece sends the spark that ignites the evaporated fuel within the system. The explosion gives the engine the ability to generate power. Though a simple part, it is necessary to the function of your Harley-Davidson. It provides an electrical arc that gets sent between two close, but not touching, parts. The charge jumps between them, and this is the energy you use to get the gas combustion needed to drive. Now, naturally, a faulty spark plug is going to cause a huge range of issues. Best case scenario, your engine will stutter. Worst case scenario, it can have a trickle effect that will damage the entire ride. To help you avoid these issues, we’ve tracked down the best spark plugs for Harley-Davidsons available on the market.

The Best Spark Plugs For Harley-Davidsons

The NGK Iridium Spark Plug is an excellent choice for dedicated Harley-Davidson riders thanks to its sturdy design and high-performance value. It comes in a set of two pre-gapped spark plugs that fit seamlessly into your motorcycle. The electrodes are made out of iridium, enabling the plug to take up substantially less space than an platinum counterpart. This small stature doesn’t impact its ability to make a spark; rather it causes the plug to be more versatile and efficient. It enables the electrical signal to run at a lower voltage, thus keeping the ignition setup working better and for longer. The spark plug is made out of heavy-duty material that, while still lightweight, holds its position while you ride. It results in a reliable spark to cause combustion and keep your bike on the road. 

Despite the high-quality design, this spark plug is not compatible with all Harleys on the market. Be sure to check the specifications before making your pick to avoid issues with fit and performance.

Key Features
  • Made using iridium and nickel
  • Incorporates powerful insulation
  • Ribbed sides corrugated for strength
  • Material has a high melting point
Specification
  • Brand NGK
  • Model DCPR7EIX-x2–6046-AZ1
  • Weight 0.01 ounces
PROS

Resistant to heat and damage

Made to last for long periods

Combusts powerfully and reliably

CONS

Not compatible with all models

Vulnerable to impact damage

Anti-seizing relies on proper install

If you want an electrical part that won’t break the bank but will perform correctly, the Quicksilver Spark Plug is worth a look. It comes as a set of two plugs, either letting you replace multiple units or keep a spare on hand. The pre-gapped design uses tungsten material to ensure a consistent charge and simultaneously prevent overheating. With a metal-plated exterior, the spark plug remains tough against a whole host of environmental damage. This includes issues related to humidity (which can cause rust and corrosion). The tough yet lightweight construction makes the spark plug easy to install on your bike. When in place, it works effectively and helps prevent combustion issues common to starting your motor with incomplete combustion. 

While cost-effective, this spark plug can be vulnerable to breakage upon impact. As a result, aim to install it quickly after receiving it to keep it away from the risk of dropping or other damage.

Key Features
  • Includes tungsten electrode
  • Designed to replace the broken part
  • Solid electrical terminal
  • Made using iridium material
Specification
  • Brand Quicksilver
  • Model 97182Q
  • Weight 0.63 ounces
PROS

Prevents rust and corrosion

Works on multiple vehicle types

Creates a powerful spark

CONS

Not compatible with all vehicles

Vulnerable to impact damage

Can wear down if installed incorrectly

With a quality design that touts universal compatibility, the E3 Spark Power Sport Spark Plug is a great choice for serious riders. It is crafted to work within a huge range of temperatures, so you don’t have to worry about extreme hot or cold. The plug is crafted using a heavy-duty steel material that reinforces the entire structure. It is sturdy enough to be resistant to ambient vibrations common to motorcycling. Especially since these vibrations can cause the plug to loosen its connection, the yttrium inclusion in the design is very helpful. It is durable and capable of lasting over long periods. With a 5/8-inch hex size, you can use it on just about any ride. 

Keep in mind that while this high-quality spark plug has a premium design, it is not invulnerable. This means that it is important to install it properly and practice routine maintenance on the bike as a whole.

Key Features
  • Measures 1 x 4 x 6 inches
  • Can replace factory plugs
  • Thick design to add stability
  • Made of steel and carbon
Specification
  • Brand E3 Spark Plugs
  • Model E336
  • Weight 2.08 ounces
PROS

Heavy-duty design and structure

Easy to install in your bike

Highly resistant to heat

CONS

May wear down prematurely

Decrease in power at higher RPM

Nickel plating may get damaged

Offering a strong electrode design and excellent thermal control, the Champion Replacement Spark Plug is worthy of an honorable mention. It incorporates advanced semi-conductor technology that optimizes resistance. The suppression mechanism prevents issues with combustion and ensures consistent results when you turn on the vehicle. You can use this spark plug on all types of vehicles with small engines, making it a versatile spark plug. It includes a copper interior that conducts well. While the efficient electrical mechanism can induce a lot of heat, it is coupled with a tough steel exterior. This makes the plug much less vulnerable to heat. It is coated with a sealant that is meant to prevent damage from rust and corrosion. Long-lasting and effective, this popular spark plug is a good way to go. 

It’s worth noting that while the spark plug has a lot of safety features, the coating outside it can get scratched or damaged. This can result in issues with the metal casing. To prevent this, ensure proper storage and installation.

Key Features
  • Designed for universal fit
  • Meets SAE and ISO standards
  • Made of copper and steel
  • Measures 4 x 4 x 1 inches
Specification
  • Brand Champion
  • Model 404
  • Weight 2.4 ounces
PROS

Compatible with any setup

High-end semi-conductor tech

Resistant to damage from heat

CONS

May be packaging issues

Exterior metal vulnerable to scratches

Can be damaged by impact

Best Spark Plugs For Harley-Davidsons Buying Guide & FAQ

When it comes time to switch out your spark plugs, it can be tricky to identify the correct part. While these parts seem relatively straightforward, it can be a bit challenging to find something that is both compatible and made out of the right materials. The spark plug needs to be strong and capable of holding up against extreme heat and electrical charges. It has to work with your entire vehicle, from the motorcycle battery to the fuel system. 

Plus, it is about more than finding something made out of the proper metal. You need a structure that can hold steadily in place without coming loose due to vibration. To find the right fit, it’s important to choose a plug that has a proven track record of success. Ultimately, the test for spark plugs is about their ability to not only work but to work over long periods. When you find something long-lasting and powerful, you can reap the most advantages from the replacement part. 

Why Do You Need Spark Plugs For Harley-Davidsons?

Perhaps the most noteworthy advantage of spark plugs for your Harley is the fact that they give you reliable and consistent combustion. By ensuring that the gas fumes explode safely, your whole engine system can last longer and work better. It also results in your wasting less fuel and limiting the risk of flooding the engine. 

When you get a proper spark plug that fits well in your motorcycle, the part can improve the overall function of your ride. It improves the quality of emissions by ensuring complete combustion of your fuel. Incomplete combustion can leave behind detrimental particles that impact the environment. 

Plus, the convenience of getting your engine to start smoothly makes swapping out your spark plugs a really good decision. Not only does it save you the hassle of facing issues with your bike, it just makes the whole experience better. From improving fuel economy to helping the environment, there is no shortage of benefits to getting new spark plugs. 

  • Ensure proper combustion of the fuel in your motorcycle. 
  • Prevents the risk of flooding your engine when starting the vehicle
  • Improves your overall fuel economy by preventing waste. 
  • Reduces your carbon footprint by mitigating the risk of dangerous emissions. 
  • Allows your vehicle to start smoothly regardless of the ambient temperature. 
  • Easy part to switch out on your own, whether you’re a professional or beginner.
Harley Davidson Details Close
Best Spark Plugs For Harley Davidson

Different Kinds of Spark Plugs For Harley-Davidsons

Though all spark plugs share the main features, the mechanism to get the spark differs by type. Each is crafted using unique materials that offer different benefits. Some riders are very specific about the type of spark plug they choose while others focus more on compatibility. By familiarizing yourself with the different types of spark plugs, you can find the best fit for your purposes.

Copper 

Representing the most common kind of spark plug on the market, you are likely to come across a lot of options within this type. The tip of the plug is made out of copper. This material has proven effective at conducting electricity in various settings. These reliable traits of the metal mean that it will work consistently. 

Though copper has predictable electrical features, it also has some downsides. The material is easy to heat up. Continual heating and cooling of metal can alter its molecular structure. Despite the copper part being fairly large, it will likely wear down sooner than other available selections. That said, copper spark plugs are a tried and true technology. 

Platinum 

Another frequently found spark plug type is platinum. Priced higher than their copper counterparts, they are less conductive as well. However, the metal is very sturdy and long-lasting. When the internal electrical parts are properly made, the platinum material can conduct reliably and ensure proper combustion of the fuel. 

As a result of the lower charge on this material, it is a lot more durable. Whether the platinum part is single or double will also impact its lasting power. Double platinum spark plugs reinforce the electrical features. It effectively provides a spark and isn’t as vulnerable to temperature-related issues. If long-term use is your focus, then a platinum-type plug may be a good way to go. 

Iridium

Incorporating a small wire at the center, these spark plugs are a high-end solution that is geared towards demanding drivers. The electrode is made out of this highly conductive material. It improves the overall efficiency of the firing component and thus improves fuel efficiency. Keep in mind that, since iridium is a rarer metal, the spark plug will be priced proportionately higher. 

The power of the electrode also enables a smaller structure. The metal takes up less space, making the entire spark plug lighter and more energy-efficient. It works reliably and is designed to last over long periods. Those looking for a high-quality option that will work well and last can easily benefit from this type of plug. 

Features to Look for in Spark Plugs For Harley-Davidsons

There are a few essential features to any spark plug. The quality and performance ability of your spark plug relies on how effective these features are, as well as their ability to integrate into a whole part. The first step is to determine the quality of each feature and use that information to determine whether the spark plug will work properly as a whole unit. 

Shell

The shell is an essential feature of the functionality of the spark plug. It consists of a threaded metal exterior that is separate from the central electrode. The separation ensures the smooth flow of electricity while also keeping the impact of heat as low as possible. 

This is the part that will make a physical connection with your vehicle. The thread and shape of the shell will determine the compatibility. When you are checking into this feature, look at the specifications on both the part and your vehicle. 

Insulator

The part that keeps the shell separate from the electrode, the insulator is made out of a ceramic material. It is inert, meaning a charge won’t pass from the electrode to the shell. The importance of the insulator can’t be understated, since it is critical to preventing wear and tear on the system. 

It not only prevents damage from the heat, but it also controls the electrical charge. The insulator is, essentially, a safety feature on your spark plug. Be sure that the ceramic is thick enough to provide sufficient security. Additionally, the quality of the ceramic itself will impact the performance. 

Electrode

Possibly the most important part of the spark plug, this is the part that creates the namesake spark. It can be made out of a host of different materials. The type of metal used in construction will dictate the type of spark plug you’re using in your motorcycle. 

In many cases, the electrode will also feature a resistor inside of it. This connects through a wire (that is insulated for protection) to the terminal on your ignitor coil. By generating the spark that combusts the fuel, the electrode feature makes itself a critical part of the spark plug itself.

Harley Davidson engine
Best Spark Plugs For Harley Davidson

What to Consider When Choosing Spark Plugs For Harley-Davidsons 

After assessing the features in your spark plug, there are a few additional considerations that will help you determine if you’ve found the right fit. By gaining a full understanding of your options, you can make the best choice. Considerations range from the material to the overall durability to performance. 

  • Compatibility: Once you’ve determined that the features of the spark plug hold up to scrutiny in terms of design and material, it is a matter of finding a good fit. Ultimately, you need to be able to get the spark plug into your vehicle. Plus, once it’s there, the plug needs to remain stable while you drive. Even a slight difference in fit can result in failure. Consult the specs for your bike to ensure that you get the right spark plug. 
  • Installation: Now that you know that you can get the spark plug to fit, you need to consider how tricky it’s going to be to install. While most spark plugs are inherently similar in this regard, it’s important to think about what you’ll need beforehand. Will you be able to use standard tools? Can you do it yourself? In most cases, you won’t need many supplies to get the job done. 
  • Durability: Finally, you’ll want to consider how long you can expect it to work. Think about the type you’re choosing and whether it’s meant to withstand the wear and tear of the road. It’s a matter of how often you ride your bike and the climate in your area. If you’re going to be using it a lot, it may be worth the investment to spring for a higher-end type of spark plug

Care and Maintenance for Spark Plugs For Harley-Davidsons

To properly care for your spark plugs, there are a few important steps to take. The main part of proper maintenance lies in the installation process. So long as you do this part properly, the spark plug can last for a long time. However, if you’re new to installing spark plugs, it can be easy to skip a step. 

The first thing you need to take care of is disconnecting the electricals. Take the lead out and clean the area around the plug. Removing the debris throughout the combustion chamber will make a huge difference. It prevents debris from getting in when you install it. Remove the spark plug using a fitting socket. Finally, clean any deposits on the plug (if it’s routine maintenance). Otherwise, you can simply place the new plug in, reattach the lead, and get back on the road. 

There are a few things to keep in mind when you’re dealing with the spark plug, both in terms of install and upkeep. 

  • Use proper tools for the removal of the spark plug, making sure that the socket is compatible. 
  • Clean the area thoroughly using correct tools like a wire brush or a spray cleaner. 
  • If you are checking on a spark plug, clean the base before replacing it. 
  • Avoid impact to the spark plug to prevent the electrode from loosening. 
  • Make sure that the spark plug is compatible with your motorcycle. 
  • Keep spare spark plugs in case of emergency along with your other motorcycle accessories.
  • Change your spark plugs at the same time to optimize the performance of your vehicle. 
  • Store your motorcycle indoors to mitigate the risk of rust and corrosion due to moisture.
  • If you can’t keep your bike indoors, use a motorcycle cover to keep the bike’s parts protected. 
  • Check on your spark plugs from time to time to ensure that there is no buildup or damage.

Best Spark Plugs For Harley-Davidsons FAQ:

When it comes to spark plugs, there are inherent similarities to each plug. There are also fine differences between different makes and models. It’s normal to have questions about installation, maintenance, and finding the right fit. We’ve addressed the most common inquiries to help you stay as informed as possible. 

Q: How often should you change Harley spark plugs?

You should change the spark plugs roughly every 30,000 miles traveled. Check their function when you do your regular maintenance, along with brake pads and tires. 

Q: What are the best spark plugs for Harley-Davidsons?

The best spark plug for your Harley is compatible, durable, and reliably supplies a spark to ensure proper combustion. A good way to go is the NGK Iridium Spark Plug.

Q: Does it matter what kind of spark plugs you use?

It’s important to find a spark plug that fits with the design of your engine. Beyond that, it’s about efficiency, reliability, and durability of the plug. 

Our Top Pick

After careful consideration, we’ve named the NGK Iridium Spark Plug as our top pick. Not only is it designed for optimal performance with Harley Davidson motorcycles, but it is also made out of high-quality materials. A strong design and excellent performance set this spark plug apart from the rest. 

Final Thoughts

Now that you’re familiar with the world of spark plugs for Harley-Davidson bikes, you can make your pick. It could be the NGK Iridium Spark Plug or the cost-effectiveness of the Quicksilver Spark Plug. A good motorcycle deserves an equally effective spark plug to keep it in optimal condition, and there’s a choice available for every bike. Happy riding!

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