NGK Laser Iridium Spark Plug Box of 4 (LMAR8BI-9) - 91909

The NGK Laser Iridium Spark Plug LMAR8BI-9 (Part #91909) is a premium iridium spark plug engineered for performance enthusiasts and powersports riders who demand consistent ignition and long service life. Sold here as a box of 4, this NGK iridium spark plug is purpose-built for high-tech, high-performance engines — including Suzuki V-Strom and GSX-series motorcycles — where standard copper plugs simply can't keep up. If you're searching for NGK spark plugs that combine durability with a reliably stable spark, the LMAR8BI-9 delivers exactly that.

Key Features & Benefits

• Fine-Wire Iridium Center Electrode (0.6mm): The ultra-small 0.6mm iridium center electrode concentrates spark energy for a consistently stable ignition event — critical in high-revving powersports engines where misfires cost power and efficiency.
• Iridium Alloy with Extremely High Melting Point: Iridium's resistance to heat and wear means this plug holds its gap and performance characteristics far longer than conventional materials — NGK rates longevity at up to 100,000 miles.
• Platinum Taper-Cut Ground Electrode: The platinum ground electrode with taper-cut shape reduces quenching and improves flame kernel growth, helping combustion propagate more completely after ignition.
• Trivalent Metal Plating: Provides superior anti-corrosion and anti-seizing properties on the shell, making future plug removal cleaner and protecting threads in aluminum heads — especially important at the specified 7.2–8.7 lb-ft torque for aluminum applications.
• Pure Alumina Silicate Ceramic Insulator: Delivers superior dielectric strength and better heat transfer, reducing the risk of pre-ignition and keeping the plug operating in its correct heat range (Heat Range 8).
• Corrugated Ribs on Insulator: Prevent flashover — electrical current jumping externally along the insulator — which can cause misfires and damage ignition components.
• Copper Core: Aids in heat removal from the center electrode, helping the plug self-clean and maintain proper operating temperature across varied riding conditions.
• Triple Seals: Three seals between the insulator and shell prevent combustion gas leakage, maintaining cylinder pressure and protecting the ignition system from hot gases.
• Built-In Resistor (5k Ohm): Suppresses electromagnetic interference that can disrupt modern engine management systems, sensors, and electronics — essential for today's fuel-injected powersports bikes.

Specifications

• NGK Part Number: 91909
• NGK Plug Code: LMAR8BI-9
• Shell Thread Diameter: 10mm
• Thread Pitch: 1.0mm
• Seat Type: Gasket
• Reach: 26.5mm (1.04")
• Hex Size: 9/16" (14mm)
• Terminal Type: Threaded Stud
• Gap: .035" (0.9mm)
• Center Electrode Material: Iridium — Fine Wire, 0.6mm
• Center Electrode Projection: Non-Projected
• Ground Electrode Material: Platinum — Standard, Taper Cut
• Resistor: Yes — 5k Ohm
• Heat Range: 8
• Torque — Cast Iron Head: 7.2–10.8 lb-ft
• Torque — Aluminum Head: 7.2–8.7 lb-ft
• Rated Longevity: 100,000 miles
• Warranty: 60 days
• Quantity in Box: 4 plugs

Fitment

The NGK LMAR8BI-9 (91909) is a powersports application plug — NGK's own fitment data lists no automotive applications for this part number. Confirmed powersports fitment includes the following (always verify your specific engine configuration before ordering):

• 2024 CFMOTO 450NK (Base)
• Suzuki DL1050 V-Strom 1050 — 2020, 2023, 2024 (Base)
• Suzuki DL1050 V-Strom 1050DE — 2023, 2024 (Base, Adventure)
• Suzuki DL1050 V-Strom 1050XT — 2020, 2022 (Base, Adventure)
• Suzuki DL800 V-Strom 800 — 2024 (Base, Touring)
• Suzuki DL800 V-Strom 800DE — 2023, 2024 (Base, Adventure)
• Suzuki GSX-8R — 2024 (Base)
• Suzuki GSX-8S — 2023, 2024 (Base)
• Suzuki DL1000 V-Strom — 2014, 2015, 2016 (ABS, ABS Adventure), 2018 (Base, XT), 2019 (Base, XT Adventure)

This plug has a 10mm thread diameter and gasket seat — do not install in an engine calling for a different thread size or tapered-seat plug. If you're unsure whether the LMAR8BI-9 fits your specific bike, contact our fitment team before ordering.

What's in the Box

• 4x NGK Laser Iridium Spark Plugs — LMAR8BI-9 (Part #91909)

Why Buy from ThreePiece.us

At ThreePiece.us, we take fitment seriously. Our team can help you confirm the LMAR8BI-9 is the right NGK iridium spark plug for your specific motorcycle before you check out — no guesswork, no returns headache. Every order ships free, and if you'd rather spread out the cost, Affirm financing is available at checkout so you can get your plugs now and pay over time. Whether you're doing a routine service on your V-Strom or prepping a GSX-8R for a season of hard riding, we're here to make sure you get the right part the first time.

Frequently Asked Questions

Q: Does this listing include 4 spark plugs or just 1?
A: This listing is sold as a box of 4 NGK Laser Iridium spark plugs (LMAR8BI-9 / 91909), making it convenient for twin-cylinder bikes that require two plugs per cylinder or for stocking a spare set.

Q: What is the correct installation torque for these plugs?
A: NGK specifies 7.2–10.8 lb-ft for cast iron heads and 7.2–8.7 lb-ft for aluminum heads. Most modern motorcycle engines use aluminum cylinder heads, so stay toward the lower end of the range and use a torque wrench to avoid thread damage.

Q: Do I need to re-gap these plugs before installation?
A: The LMAR8BI-9 comes pre-set to a .035" (0.9mm) gap from the factory. NGK generally advises against re-gapping fine-wire iridium plugs, as bending the electrode can damage the ultra-thin 0.6mm iridium tip. Verify against your service manual's specified gap before installation.

Q: Will this spark plug fit my car or truck?
A: According to NGK's own fitment data, the LMAR8BI-9 (91909) has no listed automotive applications — it is a powersports-specific plug. If you need an NGK iridium spark plug for a passenger car or truck, contact our team and we'll help identify the correct NGK part number for your vehicle.