The Best Spark Plugs For Harley Davidson: Buyers Guide

If you’re looking for the best spark plugs for your Harley Davidson motorcycle, you’ve come to the right place. We’ve got a great selection of top-quality spark plugs that are perfect for Harleys.

So whether you’re looking for a performance upgrade or need a new set of plugs, we’ve got you covered. Check out our selection and find the perfect plugs for your bike today!

But before moving on, let’s see what a spark plug is?

Spark plug – a device that helps your bike run better, and it’s essential to choose the right one. It conveys electric currents from the ignition to the engine’s combustion chamber, igniting the compressed air and fuel. 


How to Choose the Best Spark Plugs for Harley Davidson

Being a Harley Davidson rider, you know your bike needs the best spark plugs to start better and boost the engine’s performance. Typically, it’s good to change spark plugs regularly for the best performance.

Here are a few things to think about when choosing spark plugs:

-The type of engine you have

-The type of riding you do

-The climate you live in

Once you know what to look for, choosing the right spark plugs for your bike is easier.

The following is a list of the best spark plugs to help you get the best performance from your Harley Davidson.

The Best Spark Plugs for Harley Davidson List

NGK Iridium IX DCPR7EIX Spark Plugs for 1999-2016 Harley Davidson Twin Cam (Pair)


Harley riders need high-quality spark plugs that can withstand a lot of vibration and knock. NGK plugs are made from a fine wire center electrode, copper core, and iridium alloy tip. The nickel electrodes have an extremely high melting point and come with a trivalent metal plating sealed in a pure alumina silicate ceramic insulator with corrugated ribs. 

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These spark plugs provide extreme thermal resistant properties, excellent electrical insulation characteristics and are designed to withstand a lot of vibration and knocking.

The threads on this model are 12mm at a 1.25mm pitch, and the seat is a rubber gasket. This means that the model comes with a 5K Ohm resistor, has a reach of 19mm, and a gap of .031″. The terminal uses a removable nut, and the overall height is rated as JIS.

Our Recommendations:

Spark plugs can be a generic fit for many applications, but it’s crucial to check manufacturer requirements and gap the plug before installation. Riders of Harley Davidson motorcycles know that this is important for the performance and longevity of their bikes. With the right spark plugs and proper care, your Harley will run like a dream for years to come.

E3 Spark Plugs E3.36 Powersports Spark Plug, Pack of 1


The E3.36 Spark Plug is an excellent choice for Harley Davidson riders. This spark plug is designed specifically for modern Harley Davidson bikes, and it comes with a 12mm reach and uses a gasket seat design.

Its patented DiamondFIRE ground electrode uses two legs to attach to your shell, optimizing heat transfer and providing additional absorption of intense vibration. Plus, it comes with a handy storage bag to keep your spark plug in top condition when you’re not riding!

E3 Spark Plug E3.36 Powersports Spark Plug is perfect for motorcycles, ATVs, UTVs, and PWCs with 12-volt systems. It is a copper core nickel model with a 5/8 hex. The electrode is rigid and preset, so you cannot adjust it. This model comes with a 5K Ohm resistor.

Our Recommendations:

E3 Spark Plug E3.36 Powersports Spark Plug is the best spark plug for Harley riders. If you have a 2014-2016 Street Glide Special FLHXS model, this is the only spark plug we highly recommend you to use.

Champion Copper Plus 404 Spark Plug


Champion Copper Plus 404 Spark Plug is a great choice for Harley riders. It has a corrosion-resistant zinc shell and high voltage so that you can be sure of the best performance on your engine. The faster ignition also leads to better performance under all conditions.

The Champion Copper Plus 404 Spark Plug is a heat-activated alloy plug with a ground electrode and fine wires. It offers powerful performance and can reach high temperatures without losing its edge. The sharp spark focus ensures a great ride every time.

Our Recommendations:

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It is highly recommended for Harley-Davidson 1984-2000 Evolution Models.

Iridium Performance Spark Plugs Pair for Harley Softail Slim Twin Cam repl. Harley# 6R12


Iridium Performance Spark Plugs are the ultimate in technology and performance. The smaller electrode requires less voltage, resulting in a hotter spark and extended service life. 

The black ceramic with gold-colored corrosion-protected coating on the metal shell makes these plugs unique and attractive. Sold in pairs, they replace Harley# 6R12 / NGK# DCPR7EIX plugs and are perfect for Harley Softail Slim Twin Cam riders.

Our Recommendations:

Iridium Performance Spark Plugs tiny electrode requires less voltage and gives you better performance than standard plugs. Plus, they come in a pair so that you can replace them both at once.

NGK 6046 DCPR7EIX Spark Plug (Pack of 2)


If you’re peeking for a spark plug that will help you get the most out of your Harley 103, look no further than the NGK 6046 DCPR7EIX Spark Plug. It offers an instant ignition, better throttle reaction, and excellent anti-tangling, making it ideal for riders who want the best performance.

These NGK spark plugs are perfect for Harley Davidson motorcycles. They have a high melting point for better engine performance, and they also offer better strength and heat transfer core for heat removal. Plus, their triple seal prevents leakage. And finally, their electrode enhancement ensures a stronger spark.

Our Recommendations:

Here’s the catch – the adjustments are weak for the NGK 6046 DCPR7EIX Spark Plug. It’s also inefficient when it comes to fuel.


Which is a better spark plug material for Harley Davidson, iridium or platinum?

Iridium and platinum are both excellent materials for spark plugs in Harley Davidson motorcycles. They have different properties, so that one may be a better fit for your bike than the other. Platinum is less expensive, but iridium lasts longer. Talk to your mechanic to see which would work best for you.

How often should you change spark plugs on a Harley?

Most people think that spark plugs only need to be replaced every 10,000 miles, but I think it’s a good idea to check them every 4,000 to 5,000 miles. That way, you can ensure they’re in good condition and won’t need to be replaced until 10,000 miles have passed.

What are the best sparkplugs used in Harley for fuel economy?

The best spark plugs for fuel economy often depend on what type of engine your Harley Davidson has! Some engines run better with platinum or iridium-tipped spark plugs – which help reduce emissions and mileage – while others do better with copper or steel, which improves performance and wear without sacrificing as many miles per tank. Your best bet is to go to an extra-fuel Mileage Shop near you, where they can answer any questions about how to enhance your Harley’s fuel efficiency best!

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Do spark plug brands matter in Harley motorcycles?

When it comes to spark plugs for Harley Davidson riders, you need to consider a few key points. The most significant thing is that you use the right type of plug for your engine. You also want to make sure you buy a quality brand, ensuring better performance and longer life.

What’s the best spark plug for performance?

The best spark plugs on the market are iridium. Iridium spark plugs give you better gas mileage, performance, reliability, and longevity than double-platinum plugs.

Do expensive spark plugs make a difference?

Yes! Expensive spark plugs have a higher grade electrode, making them stronger and more reliable. This leads to better performance in your Harley-Davidson engine. Best of all, you can save money by choosing a high-quality brand like NGK instead of cheap brands that offer low-quality materials and don’t last very long.

What is the expected life span of Iridium spark plugs?

There are many types of spark plugs. The average modern one should last for 3-4,000 hours (or three to four thousand hours) of engine uptime. It depends on the gas quality. Each make and brand of spark plug should come with its own estimated rating for hours of use without degradation or failure.

Is it possible to mix platinum and iridium spark plugs?

It’s not advised unless you have no alternative in an emergency. They should all be identical to minimize stress on the coils and ensure that the electrical system output is balanced. Iridium plugs are a fantastic choice since they burn cleanly and maintain their gap for far longer than ordinary outlets.

If you mix spark plug types, what happens?

Misfiring can be caused by incorrect or mismatched spark plugs, as well as excessive heat, quenching, increased fuel consumption, and even engine failure. It’s advisable to change all of your spark plugs at the same time and with the proper sort of spark plug to ensure smooth and constant operation.

Is it true that NGK spark plugs are the best?

NGK is one of the world’s most experienced spark plug manufacturers, with over eight decades of expertise. Years of experience developing particular sensors, connectors, and other car engine components have allowed NGK to establish a reputation as a reputable brand known for quality and consistency.

What are the warning indicators of a bad spark plug?

A few warning indicators can tell you that your spark plugs need to be replaced. One of the most common is a decrease in engine performance, such as less power or acceleration. A misfire can also be a sign of bad spark plugs, as will an increase in fuel consumption.

Do iridium spark plugs pay for themselves?

Yes, they do! The added cost is well worth it when you consider how much money and time your car would need for maintenance without them. Best of all, you’ll notice the change immediately in the smoothness and responsiveness of your engine’s start-up and running periods.

Is it possible to change spark plugs on your own?

Replacing spark plugs is a simple and inexpensive installation job that can be completed in your own garage. Although they don’t require as much attention as the other two processes, spark plugs are equally as important and must be watched carefully.

Ending Note

If you’re looking for the best spark plugs for your Harley Davidson, then look no further. In this article, we’ve listed some of the best options on the market and explained why they are so great. The plugs on this list offer unbeatable performance, fuel efficiency, and longevity. You can’t go wrong with any of these plugs. We’ve also included a buyer’s guide to help you choose the right plugs for your needs.

By Jacob - The Rider

Hi, my name is Jacob. I'm the founder of Backyard Rider Mag - a blog about motorcycles. I've studied engineering in college but decided to make blogging my career because it really aligned with what I wanted to do creatively - talk about bikes! I've been riding for 16 years now- everything from sportbikes to cruisers, dirtbikes or even dual sports. And after all these years on the road, there are still new bikes that excite me just as much as when I first started riding.

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