Are you looking for the right spark plug size for your Harley Davidson but aren’t sure which one fits your specific model? With so many variations across different Harley series and years, finding the correct spark plug can feel confusing.
That’s why we’ve put together this Harley Davidson Spark Plug Size & Compatibility Chart — a complete guide to help you quickly identify the right spark plug for your bike.
Why Do You Need a Harley Davidson Spark Plug Chart?
The spark plug is a small but critical component of your Harley’s ignition system. It delivers the spark that ignites the air-fuel mixture inside the engine, allowing your motorcycle to run smoothly.
Using the wrong spark plug can cause:
- Poor engine performance
- Misfiring or hard starts
- Reduced fuel efficiency
- Possible engine damage over time
By using the correct Harley spark plug size and heat range, you ensure:
- Optimal combustion and performance
- Smoother starts and acceleration
- Longer engine life
- Reduced maintenance issues
That’s where this chart comes in handy — it gives you the accurate spark plug part numbers and sizes for different Harley models.
Harley Davidson Spark Plug Chart (By Model)
Below you’ll find the compatibility chart for Harley Davidson spark plugs. This covers the most popular series including Touring, Softail, Dyna, Sportster, V-Rod, and Street models.
⚡ Tip: Always check your Harley owner’s manual before purchasing, as part numbers may change slightly depending on market and year.
Spark Plug Chart for Harley Touring Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| FLHT / FLHR / FLTR | 2000–2008 | 6R12 | 0.038–0.043 | Stock Plug |
| Touring Models | 2009–2020 | 6R12 or Iridium 6R12A | 0.038–0.043 | Upgrade to Iridium for longer life |
| Touring Models | 2021–2024 | 6R12 or E3.36 | 0.038–0.043 | High-performance compatible |
Spark Plug Chart for Harley Softail Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| Softail (FXST / FLST) | 1999–2006 | 6R12 | 0.038–0.043 | Standard plug |
| Softail Models | 2007–2017 | 6R12 / 6R12A | 0.038–0.043 | Compatible with EFI |
| Softail Models | 2018–2024 | M12 Iridium / 6R12X | 0.038–0.043 | Recommended Iridium for M8 engines |
Spark Plug Chart for Harley Dyna Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| Dyna (FXD, FXDWG) | 1999–2006 | 6R12 | 0.038–0.043 | Stock Plug |
| All Dyna Models | 2007–2017 | 6R12A Iridium | 0.038–0.043 | Longer life option |
Spark Plug Chart for Harley Sportster Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| Sportster 883 / 1200 | 1991–2003 | 5R6A | 0.038–0.043 | Standard |
| Sportster Models | 2004–2020 | 6R12 | 0.038–0.043 | EFI compatible |
| Sportster Iron / Forty-Eight | 2010–2022 | 6R12A Iridium | 0.038–0.043 | Performance upgrade |
Spark Plug Chart for Harley V-Rod Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| V-Rod (VRSC) | 2002–2007 | DCPR7E | 0.031–0.035 | Stock Plug |
| V-Rod Muscle / Night Rod | 2008–2017 | DCPR8EIX Iridium | 0.031–0.035 | High-performance option |
Spark Plug Chart for Harley Street Series
| Model Name | Production Year | Spark Plug Type | Gap (inches) | Notes |
|---|---|---|---|---|
| Street 500 (XG500) | 2015–2020 | CPR6EA-9 | 0.031–0.035 | OEM Fit |
| Street 750 (XG750) | 2015–2020 | CPR6EA-9 or Iridium CPR6EAIX-9 | 0.031–0.035 | Upgrade option |
| Street Rod (XG750A) | 2017–2020 | CPR7EA-9 | 0.031–0.035 | Stock Plug |
Things You Should Know About Harley Spark Plugs
- Gap Matters: Always set your spark plug gap according to the recommended spec for your Harley (usually between 0.038–0.043 inches).
- Iridium vs Standard: Iridium plugs last longer and offer better combustion but cost more than standard copper plugs.
- Signs of Wear: If your Harley misfires, idles rough, or shows poor fuel economy, check your plugs for carbon deposits or wear.
- Replacement Interval: Standard plugs usually last 10,000–15,000 miles, while Iridium plugs may last up to 30,000 miles with proper maintenance.
How to Replace Spark Plugs on a Harley Davidson
- Prepare the bike – Place your Harley on a stand and let the engine cool completely.
- Locate the plugs – Remove the spark plug wires carefully (don’t pull by the wire, use the boot).
- Remove old plugs – Use a spark plug socket and ratchet. Turn counterclockwise to remove.
- Check gap – Measure the gap of the new plugs with a feeler gauge and adjust if necessary.
- Install new plugs – Thread in by hand first to avoid cross-threading, then torque to spec.
- Reconnect wires – Push the spark plug wires back until they click securely.
- Test run – Start the engine and listen for smooth idle and acceleration.
Final Thoughts
Choosing the correct Harley Davidson spark plug size is vital for maintaining your bike’s performance, fuel efficiency, and longevity. With the help of this chart, you can easily match your Harley’s model and year to the right spark plug type.
Whether you ride a Sportster, Softail, Touring, Dyna, V-Rod, or Street, this guide ensures you’ll always pick the right fit.
Tonmoy is a recognized author and editor known for his deep passion and expertise in the world of motorcycles. His work goes beyond the mechanics and aesthetics, capturing the vibrant culture of motorcycle clubs and the strong sense of brotherhood shared by riders. Tonmoy’s special enthusiasm for motorcycle clubs adds depth to his writing, making his contributions to the motorcycle community both insightful and impactful
