A Comprehensive Guide to the Harley Davidson Spark Plug Chart

The Harley Davidson spark plug chart is an essential tool for every Harley owner. It helps you determine the correct spark plug type and specifications for your motorcycle.

These specifications ensure optimal Performance and fuel efficiency. Spark plugs are small devices that help ignition your motorcycle. They help burn the fuel well and ensure the engine’s smooth running. The Harley spark plug chart helps you choose the right one based on your bike’s specifications.

Here, take a comprehensive look at the Harley Davidson spark plug chart, how it can help optimize Performance, and what benefits you can reap from it. We will also include instructions on identifying the correct spark plug for your bike and replacing it safely and correctly.

Harley Davidson Spark Plug Chart

Types of Spark Plugs 

Types of Spark Plugs 

Harley Davidson has several spark plugs, including conventional, electronic, and wet spiral. Conventional plugs have a center electrode that is made of platinum or iridium. These plugs provide high spark energy and top Performance.

Electronic spark plugs use electronics to control the voltage and frequency of electricity to produce sparks. Wet-spiral sparkplugs are made of copper-coated electrodes that spiral around a central electrode. These plugs provide high plug heat and resistance to fouling.

In addition, they can withstand extreme temperatures without damage. Finally, specialty sparkplugs like those for throttle bodies or fuel injectors help improve Performance and durability for specific applications. For your kind information, there is a difference between lead and lead-free spark plugs.

A lead-free spark plug contains no lead. Lead has been banned from many consumer products because of its health risks, including the potential for children to be exposed to it if they choose to use leaded products such as paints and batteries. A lead-free spark plug is made from another material that works just as well as lead but poses fewer health concerns for consumers.

Use The Harley Davidson Spark Plug Chart For The Right Spark Plug

Use The Harley Davidson Spark Plug Chart For The Right Spark Plug

Harley-Davidson motorcycles have become an iconic American cultural symbol. Many Harley owners take pride in their bikes and are eager to keep them in top condition. To do so, they must know how to read the Harley Davidson spark plug chart.

This chart provides essential information about the spark plug required for every Harley Davidson model. It includes information on spark plug type, gap size, thread size, and reach. With this information, Harley owners can ensure that their motorcycles run at peak performance.

Spark plugs are tiny components in your engine that help convert fuel combustion into mechanical energy, allowing your vehicle to move. Engine performance and fuel efficiency improve with proper spark plugs. You can trust us to provide an in-depth understanding of these components. Let’s have a look at the Harley Davidson spark plug chart:

Harley Davidson Spark Plug Chart

ACCEL U-Groove ACCEL Platinum ACCEL Ref. No. Champion Harley-Davidson
Ref. No. Part No.
2401 137 J12YC 3 N/A
2401A Y2401 138 J18YC 3-4 32301-60
2402A Y2402P 168 H10 5 32307-58
2403 115 N9YC 5-6 32309-69
2403A Y2403P 116 N12YC 5A6A 32310-78
2410* 494 RN9YC 5A6 32310-77
2410A* Y2410P 496 RN12YC 5R6A 32311-83
2413* Y2413P 453 RL82YC 4RS 32301-80
2418* Y2418P 882 RA8HC 6R12 32317-86
2418* Y2418P 882 RA8HC 6R12 32362-04
*Indicates Resistor Style Spark PlugNOTE: ACCEL Reference Number is an actual number marked on the spark plug

How To Make Use Of A Spark Plug Chart?

How To Make Use Of A Spark Plug Chart

Using a spark plug chart can help you determine the proper spark plug for your car or truck. It shows each spark plug type’s recommended gap, voltage, and amperage. The chart also shows whether to use a platinum or an iridium spark plug.

The chart usually includes new cars but can be found online or at auto parts stores. It can also help you identify potential engine performance or fuel efficiency issues. You can use a spark plug chart to ensure your vehicle has optimal engine performance and fuel economy.

  • When using a spark plug chart, you should first ensure that your battery is good, there are no vacuum leaks, and the spark plugs are new.
  • Spark plug charts can be a valuable aid in diagnosing spark plug conditions. These charts can help identify problems with misfiring, electrode fouling, or faulty wiring.
  • Spark plugs should change roughly every 30,000 miles traveled. This will ensure the engine receives a good fuel-oxygen mixture and the best Performance. However, if you are using synthetic oil, it may extend the life of your spark plugs by up to 50 percent.
  • You can use official spark plugs for your Harley-Davidson if they are designed for your bike’s engine. This will ensure optimal performance and prevent costly repairs down the road.

Benefits Of Using The Right Spark Plug

Numerous benefits come with using the right spark plug, and it can make a huge difference in the Performance and durability of your vehicle. Choosing the right spark plug can help to optimize fuel efficiency, reduce emissions, and avoid engine damage. Choosing a spark plug with the proper heat range for your vehicle is also important.

The wrong heat range can lead to excessive heat damage or even a fire. In addition, choose a spark plug with the correct diameter for your vehicle’s cylinder head. If you use a spark plug that is too large, it could cause engine damage or even an engine failure. Choosing the right spark plug can positively impact your vehicle’s Performance and safety. Using a durable and well-made spark plug makes sense to get optimal performance from your car or truck.

Choosing The Right Spark Plug For Your Bike

Choosing The Right Spark Plug For Your Bike

You have a few options when buying the right spark plug for your bike. First, you can choose a spark plug designed specifically for motorcycle engines or one compatible with multiple makes and models. Next, you have to determine the gap setting of the plug. This refers to the distance between the electrodes that create a spark when the plug is installed in the cylinder head—finally, consider cost and longevity before making your final purchase decision.

Choosing a spark plug that matches your riding style and needs is essential. For example, if you are an aggressive rider who loves to take on difficult curves at high speeds, a spark plug with a higher gap setting may be best for you. However, a more budget-friendly option may be better for you if you are more of a leisurely biker who takes it easy on twisty roads.

Maximizing Performance With The Spark Plug Chart

The spark plug is an important part of your engine’s Performance. Maximizing Performance with the Spark Plug is about understanding the importance of spark plugs in a vehicle’s engine. Factors such as fuel quality, air-fuel ratio, and spark plug settings affect how efficiently your vehicle’s engine runs. Understanding these factors can help you maintain optimal fuel economy and overall Performance. Here are some tips for maximizing the Performance of your spark plug:

  • Replace a spark plug that’s burned out or fouled with one with higher sparks and more fuel to help you get better mileage.
  • Maintain the gap between the spark plug and the cylinder head. This will ensure a smooth and efficient combustion process in the cylinder.
  • Clean and adjust the gap of your spark plugs regularly. This helps to maintain optimal Performance.
  • Check for loose or damaged parts regularly, including the spark plugs, lead wires, and coil pack, to avoid any issues with your spark plugs.

How Does A Spark Plug Chart Help?

How Does A Spark Plug Chart Help

Spark plug charts are a valuable tool that can help optimize performance when changing spark plugs. They provide a visual representation of the condition of your spark plugs at different throttle conditions, which can help you identify areas for adjustments if rejecting your carburetors is necessary.

Spark plug charts are also useful for reading the condition of your engine’s cylinders and rings, helping you understand how well the engine is running. Finally, reading spark plugs can give an understanding of how much fuel is being consumed and how much air is entering the engine, giving you an idea of engine efficiency and overall operation. Spark plug charts are a valuable tool that can help you keep your motorcycle running smoothly and efficiently.



Spark Plugs are the electrical components that generate the spark that fuels an internal combustion engine. The spark plug of a Harley Davidson motorcycle is found in the leftmost cylinder of the engine and is fed by a metallic electrode called a spark plug boot.

The Harley spark plug chart is a good way to identify the spark plugs that suit your motorcycle. It also helps you determine the correct spark plug gap for optimum Performance. We’ve provided you with a spark plug chart for Harley Davidson motorcycles, including information on the spark plugs used in each model. Following this chart, you can determine which spark plugs are right for your bike and keep it running smoothly and efficiently. 

Frequently Asked Questions

1.How Often Should You Change Spark Plugs On A Harley Davidson?

Ans: We recommend changing plugs on a Harley-Davidson every 15,000 to 16,000 miles. When it is recommended to buy a second-hand motorcycle, ask the seller when they changed the spark plugs.

2.What Are The Standard Motorcycle Spark Plug Sizes?

Ans: Most motorcycle spark plugs have a 10mm, 12mm, or 14mm thread size. These thread diameters are the most common and are rarely seen in other sizes. Service manuals will indicate the exact type of spark plug needed for a motorcycle.

3.What Is The Normal Color Of A Good Spark Plug?

Ans: The normal color of a good spark plug is light tan or light grey. This is the ideal color as it allows you to understand the condition of the spark plug without having to remove it. Suppose the color at the insulator tip is light tan or light grey. Then the spark plug is in good condition and will not cause any problems.

4.What Are The Best Spark Plug Charts?

Ans: NGK Iridium Spark Plugs are a good choice when choosing spark plugs for Harley Davidson motorcycles. NGK iridium spark plugs have been known to provide reliable sparks and are compatible with Harley Davidson engines. Brands such as Champion, NGK, Accel, Autolite, E3, and Pulstar are all recommended for spark plugs for Harley Davidson motorcycles.

5.Are There Any Drawbacks To Using A Spark Plug Chart For Harley Davidson?

Ans: One of the main drawbacks is that a chart may only sometimes account for specific bike modifications or unique riding conditions. Additionally, some charts may need to provide accurate information on the proper spark plug gap, heat range, or other important factors that can affect engine performance and longevity.

Leave a Comment