Essential Spark Plug Guide for the 2008 Harley FXDSE2 Screamin' Eagle Dyna
Keep your high-performance Screamin' Eagle 110 engine firing perfectly with the right set of plugs.
- The OEM plug is a Harley/Champion 6R12, but many owners upgrade to NGK Iridium plugs (DCPR7EIX) for better longevity and performance on the 110ci engine.
- Always check and set the spark plug gap to .038"-.043" before installation.
- Replacement is an easy DIY job that takes less than 30 minutes with a 5/8" spark plug socket.
- While there are no spark plug recalls, the 2008 110ci engine had other factory updates, making proper maintenance even more critical.
Signs of Failing Spark Plugs
When your spark plugs are wearing out, your bike will tell you. Listen and feel for these common symptoms. Ignoring them can lead to poor performance and leave you stranded.
Choosing the Right Aftermarket Spark Plug
Your 2008 FXDSE2 is a special CVO (Custom Vehicle Operations) model with a high-output engine. Because of this, selecting the right spark plug is more than just finding one that fits; it's about maintaining the performance you expect. The original equipment (OEM) plug is a Harley-Davidson branded 6R12, which is manufactured by Champion.
Standard Plugs vs. Iridium Plugs
You have a choice between standard copper plugs and premium iridium plugs. Standard plugs, like the Champion RA8HC or NGK DCPR7E, are affordable and provide excellent performance. They are a great OEM-quality choice but need to be replaced more frequently. Iridium plugs, like the NGK DCPR7EIX, have a fine-wire center electrode made from a very durable material. This allows for a more consistent, stable spark and a much longer service life, which is a real benefit for a high-compression engine like the Twin Cam 110. Many owners consider iridium plugs a worthwhile upgrade for improved starting and longevity.
Brand Tiers: Champion vs. NGK
Champion: As the maker of the stock Harley plug, Champion (model RA8HC) offers a direct, budget-friendly replacement. They get the job done, but some riders in online forums report having better luck and more consistent performance with other brands.
NGK: NGK is a highly respected brand in the Harley community. Their standard plug (DCPR7E) and especially their Iridium IX plug (DCPR7EIX) are popular upgrades. Owners often report smoother idling and crisp performance with NGK plugs, making them a top-tier choice for your Screamin' Eagle Dyna.
Pro Tip: Check The Gap! Always check the spark plug gap before installation. Most Harley models, including the FXDSE2, require a gap between .038 and .043 inches. Use a proper gapping tool and be gentle, especially with fine-wire iridium plugs.
Known Issues & Recalls
While there are no specific recalls or technical service bulletins (TSBs) for the spark plugs on the 2008 FXDSE2, it's important to know that the 110ci engine from this era had some known issues. Harley-Davidson issued a "product program" (Recall 0906) for 2007-2008 CVO models to address potential problems with top-end gaskets and other engine components. A healthy ignition system with quality spark plugs is even more important in these high-strung engines.
Cost of New Aftermarket Spark Plugs
| Part Type | Cost Range |
|---|---|
| Standard Aftermarket (Champion, NGK Copper) | $3.91 - $7.50 per plug |
| Premium Aftermarket (NGK Iridium) | $8.00 - $14.32 per plug |
Frequently Asked Questions
How often should I change the spark plugs on my FXDSE2?
Harley-Davidson often recommends a replacement interval of every two years or 30,000 miles, but many owners do it more frequently. For a high-performance engine, replacing standard plugs every 10,000-15,000 miles is good practice to maintain peak performance. Iridium plugs can last much longer, often exceeding 30,000 miles.
Are Iridium spark plugs worth the extra cost?
For the Screamin' Eagle 110 engine, many riders say yes. The main benefits are a much longer service life and a more stable spark, which can improve starting and maintain performance over time. Given the relatively small price difference, they are a popular and recommended upgrade.
What is the correct spark plug gap for a 2008 FXDSE2?
The typical gap specification is between .038 and .043 inches. It is critical to verify the gap on new plugs before installing them, as they are not always set correctly out of the box.
Do I need special tools to change my spark plugs?
The job is straightforward and requires basic tools. You will need a 5/8-inch spark plug socket, a socket wrench with an extension, and a spark plug gapping tool. A torque wrench is also recommended to tighten the plugs to the correct specification (usually 12-18 ft-lbs).
Technical Specifications
OEM Part Numbers: 32364-04 6R12
Thread Size: 12mm, Hex Size: 5/8", Reach: 19mm (3/4"), Recommended Gap: .038" - .043"
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Harley Davidson FXDSE2 Screamin Eagle Dyna: