Best Spark Plugs For Triumph Bonneville Featuring 10 Quality Options

When I first started wrenching on my Triumph Bonneville, I quickly realized that optimizing the ignition system was the simplest way to get crisp, reliable power delivery. Few maintenance tasks impact starting and running quality as much as installing the right set of plugs. I’ve personally run through numerous iterations, and finding the best spark plugs for Triumph Bonneville models—whether air-cooled or liquid-cooled—often comes down to balancing cost, performance, and longevity. This comprehensive guide reviews 10 top-rated options, helping you dial in your Bonnie’s performance.

IMAGE	PRODUCT NAME	AMAZON LINK
	2 PCSNEW — NGK # 4929 Standard Spark Plugs –…	View on Amazon
	NGK Resistor Sparkplug DPR8EA-9 for Triumph Bonneville T100…	View on Amazon
	NGK DPR8EIX-9 Iridium IX Spark Plug	View on Amazon
	NGK Spark Plug DPR8EA-9- Set of 4	View on Amazon
	NGK Iridium Sparkplug DPR8EIX-9 for Triumph Bonneville T100…	View on Amazon
	A-Premium Iridium Platinum Spark Plugs Compatible with…	View on Amazon
	2 Pack NGK Spark Plug LMAR8A-9#4313 for Yamaha Triumph…	View on Amazon
	BDFHYK 4929 Iridium Spark Plugs Compatible with Kawasaki…	View on Amazon
	DRIVESTAR 4929 Spark Plug Compatible for 2003-2009 Honda…	View on Amazon
	NGK 5044 Iridium IX Spark Plug – BR8EIX, 1 Pack	View on Amazon

2 PCSNEW — NGK # 4929 Standard Spark Plugs — DPR8EA-9

If you’re looking for the original equipment equivalent (OEM) without the dealership price tag, the NGK 4929 Standard plug is a fantastic choice. This copper core plug delivers consistent, reliable ignition, making it ideal for routine maintenance on standard air-cooled Bonnevilles. Since it’s a standard plug, you’ll need to adhere to factory change intervals, but the 2-pack provides excellent immediate value for a twin-cylinder bike. These are genuine NGK components, ensuring they fit and function exactly as intended.

Key features that stand out:
– 2 pack NGK Standard 4929 Spark Plug
– Genuine NGK Parts—reliable OEM quality.
– Direct replacement auto parts, ensuring perfect fitment.
– Includes original packaging and hardware.

Pros:
– Very cost-effective and budget-friendly
– Reliable performance for stock engines
– Excellent heat dissipation due to copper core
– Matches OEM specification for many Bonneville models

Cons:
– Shorter service life compared to iridium plugs

Best for: Riders who prefer standard copper plugs and adhere strictly to regular maintenance schedules.

Expert Opinion: This plug is the workhorse of the Bonneville line. While it doesn’t offer the extended life of iridium, its consistent spark and excellent affordability make it the go-to standard plug for reliable everyday riding.

NGK Resistor Sparkplug DPR8EA-9 for Triumph Bonneville T100 800 2002-2006

Specifically marketed for the early T100 800 models, this NGK Resistor Sparkplug ensures that your bike runs smoothly without electrical interference in the ignition system. NGK is renowned for its manufacturing precision; this plug utilizes a triple-gasket sealing process to prevent combustion gas leakage, ensuring maximum pressure is contained. The narrow tolerances mean you get consistent quality, making it the plug of choice for millions of vehicles worldwide.

Key features that stand out:
– Triple-gasket sealing process, ensuring a secure fit.
– Consistent performance, minimizing misfires.
– Tolerances are incredibly tight, reducing manufacturing margin for error.
– Resistor type plug protects electronic components.

Pros:
– Specifically targeted fitment for T100 800 models
– Excellent sealing prevents leakage
– Reliable ignition consistency
– Manufactured by the world’s largest supplier of OEM spark plugs

Cons:
– Basic copper design requires more frequent replacement.

Best for: Owners of 2002–2006 T100 models seeking the precise OEM replacement.

Expert Opinion: Choosing a plug matched specifically to the engine generation, like this one for the 800cc air-cooled twins, guarantees optimal performance without having to worry about heat range or fitment variations.

NGK DPR8EIX-9 Iridium IX Spark Plug

The DPR8EIX-9 Iridium IX is where performance meets longevity. Designed for the enthusiast, this plug offers extreme ignitability thanks to its 0.6mm laser-welded fine Iridium tip. If you’re looking for a noticeable bump in throttle response and quicker starts, this is your upgrade. The iridium alloy is incredibly durable against heat and electrical wear, meaning you can ride longer, harder, and worry less about maintenance intervals.

Key features that stand out:
– 0.6mm laser welded fine Iridium tip for stability.
– Improved throttle response and superior ignitability.
– Longer insulator nose and triple gasket seal prevent leakage.
– Trivalent metal plating offers superior anti-seizing properties.

Pros:
– Dramatically increased lifespan over copper plugs
– Sharper throttle response and faster acceleration
– Highly resistant to fouling and electrical wear
– Excellent anti-seizing properties simplify future changes

Cons:
– Higher upfront cost than standard copper plugs.

Best for: Riders prioritizing maximum performance, extended service intervals, and superior engine response.

Expert Opinion: The shift from copper to iridium in the Bonneville fundamentally changes the required maintenance schedule. This iridium plug is one of the best investments you can make for reliable, long-term performance.

NGK Spark Plug DPR8EA-9- Set of 4

If you own a Triumph Bonneville and maybe another compatible bike or simply want to stock up, this 4-pack of the reliable NGK DPR8EA-9 is the most economical choice. You get four genuine NGK standard copper plugs, which means you have two sets ready for routine replacement. This option delivers the same dependable ignition quality as the 2-pack but offers significant savings per unit when bought in bulk.

Key features that stand out:
– 4 pack of NGK Standard 4929 Spark Plugs.
– Genuine NGK Parts and direct OE replacement.
– Includes original packaging and hardware.
– Great bulk value for frequent changers.

Pros:
– Best cost-per-plug value
– Guarantees you have a spare set for the next service
– Highly reliable standard performance
– Genuine and tested NGK quality

Cons:
– Requires storage space for the extra plugs.

Best for: Budget-conscious riders, mechanics, or those running multiple bikes that use the DPR8EA-9 standard plug.

Expert Opinion: Buying in a 4-pack is smart purchasing. Spark plugs are consumables, and having a spare set ready minimizes downtime when the time comes for service.

NGK Iridium Sparkplug DPR8EIX-9 for Triumph Bonneville T100 865 2007-2015

Designed to upgrade the ignition system on later air-cooled 865cc Bonneville models, this Iridium IX plug delivers superior performance and efficiency. Featuring a laser-welded Iridium center electrode tip and a Platinum disc welded to the ground electrode, this plug ensures maximum longevity and a powerful, consistent spark. Owners frequently report quicker acceleration, faster starts, and even slight improvements in fuel economy and reduced emissions after switching to iridium.

Key features that stand out:
– Laser welded Iridium center electrode tip.
– Platinum disc welded to backside of ground electrode provides long life.
– Trivalent Metal Plating for superior anti-corrosion and anti-seizing.
– Faster starts and quicker acceleration.

Pros:
– Optimized for the 865cc engine models
– Extremely long service life
– Excellent resistance to corrosion and seizing
– Improved starting performance in cold weather

Cons:
– Requires careful handling during installation due to the fine electrode tip.

Best for: Owners of the 865cc Bonneville who demand high performance and maximum durability from their ignition system.

Expert Opinion: The use of both Iridium and Platinum materials in this plug makes it incredibly robust. This combination is engineered specifically to handle the demands of modern engine performance tolerances.

A-Premium Iridium Platinum Spark Plugs Compatible with Honda Goldwing, Interceptor, Nighthawk & Suzuki GS500, VX800 & Triumph Adventurer, Tiger & Yamaha FJ1100, SRX600 (Pack of 4)

This 4-pack of Iridium Platinum plugs offers outstanding cross-compatibility, covering a massive range of motorcycles, including many Triumph Bonneville, Scrambler, and Thruxton models (see the extensive fitment list). The dual-metal construction (Iridium center, Platinum ground) ensures long-lasting, robust performance across varied riding conditions. While this is an aftermarket brand, the focus on extensive OE reference numbers (like DPR8EIX-9) suggests it aims to meet or exceed OEM specifications for fit and function.

Key features that stand out:
– Iridium Platinum construction for long life.
– Pack of 4 offers great value for multi-bike owners.
– Extremely broad vehicle fitment (including numerous Triumph models).
– Engineered to meet stringent OE standards.

Pros:
– Highly versatile fitment list
– Superior durability due to Iridium/Platinum materials
– Excellent value for a 4-pack of premium plugs
– Direct replacement for DPR8EIX-9 plugs

Cons:
– Not a specialized NGK plug, which some purists may prefer.

Best for: Multi-bike owners needing reliable Iridium quality across several different models, including the Bonneville.

Expert Opinion: Always double-check the extensive fitment notes for third-party plugs like this, but the use of premium metals at this price point makes it an attractive alternative to the major brands if verified fitment is confirmed.

2 Pack NGK Spark Plug LMAR8A-9#4313 for Yamaha Triumph FZ-07 MT-07 Bonneville Thrux

This specific plug, the LMAR8A-9, is highly relevant for owners of the liquid-cooled, newer generation (900cc/1200cc) Triumph Bonneville models like the Street Twin, T100, or T120 (always verify fitment). These newer engines require a different, longer-reach plug. This NGK standard plug is constructed with a pure alumina silicate ceramic insulator for superior strength and better heat transfer. The copper core aids in heat removal, making it a reliable standard choice for high-tech engines.

Key features that stand out:
– LMAR8A-9 designation for newer, liquid-cooled engines.
– Pure alumina silicate ceramic insulator for strength.
– Copper core aids in efficient heat removal.
– Trivalent metal plating for anti-corrosion.

Pros:
– Ideal fitment for many modern, liquid-cooled Bonneville variations
– Strong construction and superior heat management
– Standard plugs are easy to gap and install
– Triple seals prevent combustion leakage

Cons:
– Limited to specific newer models, not suitable for older air-cooled bikes.

Best for: Owners of modern, liquid-cooled Triumph Bonnevilles (900/1200cc) looking for a reliable standard copper plug.

Expert Opinion: Owners of the modern Bonnevilles must use the LMAR-series plugs due to the different head design. This 2-pack offers factory-recommended performance for these high-tech twin engines.

BDFHYK 4929 Iridium Spark Plugs Compatible with Kawasaki Compatible with Triumph for Yamaha for Honda for Suzuki Universal Motorcycle Spark Plugs Replacement for DPR8EA9 Set of 4

The BDFHYK 4929 set offers an Iridium upgrade housed in a highly compatible 4-pack, aiming to replace the popular DPR8EA9 standard plug. This is a direct Iridium replacement for standard 4929 plugs. They boast superior ignition performance, faster jumps, and a significant increase in power performance compared to standard copper. They are OE level durability, coming from a TS16949 certified manufacturer, giving confidence in their quality and consistency.

Key features that stand out:
– Iridium Center Electrode Material for longevity.
– Direct replacement for the standard DPR8EA9 4929 plug.
– Superior ignition performance and efficiently adapted power performance.
– OE level durability and TS16949 certified manufacturing.

Pros:
– Offers Iridium benefits at a competitive price point
– Excellent compatibility across many motorcycle brands/models
– Easy installation process
– Set of 4 provides great value

Cons:
– Less brand recognition than NGK among some Triumph enthusiasts.

Best for: Riders seeking the improved power and efficiency of Iridium while staying within a budget.

Expert Opinion: This plug targets the performance upgrade market. If you are currently running a standard DPR8EA-9, this is the simple, direct Iridium swap that should provide immediate benefits in starting and acceleration.

DRIVESTAR 4929 Spark Plug Compatible for 2003-2009 Honda CRF 230F 2002-2012 Triumph America 2008 2009 Yamaha Raider 1997-2012 Kawasaki KLR650 2004-2009 Suzuki GS500F Pack of 4

The DRIVESTAR 4929 spark plug set provides a highly reliable, aftermarket replacement for numerous motorcycle models, including the Triumph Bonneville (2005-2013). This 4-pack emphasizes superior performance with improved fuel efficiency and lower emissions. Designed for easy installation, these plugs aim to meet or improve upon the OE design. The company backs its product with a generous 3-year warranty, demonstrating confidence in its quality control and durability.

Key features that stand out:
– Pack of 4 plugs compatible with 2005 – 2013 Triumph Bonneville.
– Focus on increasing fuel efficiency and lowering emissions.
– Easy Installation matching or improving OE design.
– Backed by a 3-year warranty.

Pros:
– Strong warranty backing the product
– Claims to improve gas mileage and reduce emissions
– Designed for fast and easy installation
– Economical 4-pack option

Cons:
– Less technical detail provided on electrode material compared to NGK offerings.

Best for: Triumph owners looking for a highly compatible, warrantied, and easy-to-install aftermarket plug set.

Expert Opinion: The focus on fuel efficiency and the 3-year warranty are major selling points. For the average rider who wants reliability and value, this set offers peace of mind.

NGK 5044 Iridium IX Spark Plug – BR8EIX, 1 Pack

While the BR8EIX is typically used in two-stroke engines or specific high-revving applications (like dirt bikes or some early Triumph triples), it’s reviewed here to highlight the diversity of NGK’s Iridium line. This single-pack Iridium plug uses the signature fine wire center electrode for high durability and a stable spark. The Iridium alloy’s extremely high melting point makes it highly resistant to thermal and electrical breakdown. For a Bonneville, you need to ensure this heat range (8) is appropriate for any high-performance modification you may have, as it’s generally a colder plug than the recommended DPR8.

Key features that stand out:
– Fine wire center electrodes ensure high durability.
– Iridium alloy has an extremely high melting point.
– Pure alumina silicate ceramic insulator provides superior strength.
– Copper core aids in heat removal.

Pros:
– Highest durability Iridium construction
– Extremely stable spark under harsh conditions
– Excellent heat transfer properties

Cons:
– BR8 heat range is usually too cold for a standard Bonneville (DPR8 required), meaning this is highly specific to tuned engines.
– Sold as a single pack, requiring multiple purchases for a twin.

Best for: Tuned or high-performance Bonneville variants that specifically require a colder heat range (always check your tuner’s specifications).

Expert Opinion: Do not install this plug in a stock Bonneville unless advised by a professional mechanic or tuner. Using the wrong heat range (colder than necessary) can lead to fouling and poor idle performance.

Spark Plug Comparison Insights

Choosing the right spark plug for your Triumph Bonneville often boils down to balancing cost versus longevity.

Standard Copper (DPR8EA-9) plugs are the benchmark for reliability and are incredibly affordable, especially when purchased in 4-packs (NGK Spark Plug DPR8EA-9- Set of 4). They offer consistent performance and excellent heat transfer, but you must replace them at or before the factory-recommended interval (usually every 6,000 to 8,000 miles). They are the best choice for riders prioritizing budget.

Iridium (DPR8EIX-9) plugs are the premium upgrade. While the initial cost is higher, the extended lifespan (often 2-3 times longer) and the marginal performance improvements (sharper idle, better starting) make them worthwhile. If you hate frequent maintenance, the NGK DPR8EIX-9 Iridium IX Spark Plug is the clear winner for longevity and performance.

Crucially, modern liquid-cooled Bonnevilles (900/1200cc) require a completely different fitment, exemplified by the NGK LMAR8A-9. Installing the wrong size or reach plug will cause severe engine damage, so always verify the engine generation before purchasing.

Final Verdict

Deciding on the best spark plugs for Triumph Bonneville involves knowing your bike’s generation and your riding priorities.

The Best Overall Performer: The NGK DPR8EIX-9 Iridium IX Spark Plug (or the specific DPR8EIX-9 4-pack alternative). Iridium provides the superior spark stability, corrosion resistance, and dramatically extended maintenance intervals, making it the smartest long-term investment for the air-cooled twin.

The Best Value Option: The NGK Spark Plug DPR8EA-9 – Set of 4. If you don’t mind changing plugs more frequently, this 4-pack offers unmatched cost efficiency while still providing the proven quality of NGK copper plugs.

For Liquid-Cooled Models: Owners of the newest Bonnevilles should rely on the specific fitment provided by the 2 Pack NGK Spark Plug LMAR8A-9#4313, ensuring that the specialized needs of the liquid-cooled heads are met.

Best Spark Plugs For Triumph Bonneville FAQ

Q: What is the recommended spark plug gap for a Triumph Bonneville?

A: For most air-cooled Triumph Bonneville 800cc and 865cc models using the standard DPR8EA-9 or DPR8EIX-9 plugs, the typical gap is 0.8mm to 0.9mm (or 0.032 to 0.035 inches). Always confirm this measurement in your specific owner’s manual, as modern liquid-cooled models (using LMAR-series plugs) may have different specifications.

Q: How often should I change my Bonneville spark plugs?

A: Standard copper plugs (DPR8EA-9) should generally be replaced every 6,000 to 8,000 miles or at the factory-specified interval. If you upgrade to Iridium plugs (DPR8EIX-9), the interval can often be extended to 16,000 miles or more, provided the bike runs cleanly.

Q: Are standard copper plugs (DPR8EA-9) sufficient for my Bonneville?

A: Yes, the DPR8EA-9 copper plug is the standard OEM plug for many air-cooled Bonnevilles and provides reliable, efficient operation. While Iridium plugs offer a longer lifespan and marginally sharper response, the standard NGK plugs are perfectly sufficient for everyday use and routine maintenance.

Q: What is the heat range difference between DPR8EA-9 and DPR9EA-9 plugs?

A: The number “8” in DPR8EA-9 indicates the heat range. NGK uses a system where a higher number indicates a colder plug. The stock Bonneville requires the heat range “8”. A DPR9 plug would be a colder plug, potentially leading to fouling if installed in a stock engine. Sticking to the factory-recommended heat range (8) is essential for Triumph Bonneville engine health.

Q: Do I need a resistor-type spark plug for my Bonneville?

A: Yes. All modern Triumph Bonneville bikes use electronic ignition systems and require resistor plugs (indicated by the ‘R’ in the NGK model name, e.g., DPR8EA-9). The resistor helps suppress radio frequency interference (RFI) that could disrupt the bike’s electronic components, such as the digital tachometer or ECU.

Q: Should I use Iridium or Copper plugs if my Bonneville is heavily modified?

A: For heavily modified or high-performance Bonneville engines (especially those with high compression or forced induction), Iridium plugs are generally recommended. Their superior ignitability and resistance to thermal breakdown make them better suited for the higher demands and temperatures of tuned engines. Always check if the modifications require a colder heat range.