NGK CR9EIX Iridium IX Pack of 3 – NGK CR9EIX Iridium IX Spark Plugs x3
Pack of 3 genuine NGK CR9EIX Iridium IX spark plugs, NGK stock number 3521. The three-pack is particularly useful for compatible three-cylinder motorcycles where all plugs are replaced as a set.
What You Receive
- 3 x genuine NGK CR9EIX Iridium IX spark plugs
- NGK retail packaging / identification as shown in the product image
CR9EIX Specifications
- NGK plug code: CR9EIX
- NGK stock / manufacturer number: 3521
- Range: Iridium IX
- Quantity: 3 genuine NGK spark plugs
- Thread diameter: 10 mm
- Thread pitch: 1.0 mm
- Thread reach: 19 mm
- Hex / wrench size: 16 mm
- Heat range: 9
- Resistor type: yes (R in CR9EIX)
- Seat: gasket / flat-seat type
- Centre electrode: fine-wire iridium, approximately 0.6 mm
Why Iridium IX?
NGK uses a very fine iridium centre electrode to improve ignitability while resisting spark erosion. NGK lists CR9EIX as the advanced iridium option for many applications that use a CR9E/CR9EK-family standard plug.
Fitment Guide
- General application: CR9EIX is used across many motorcycles, scooters and powersports engines. Confirm CR9EIX / NGK 3521 against the exact vehicle before ordering.
- Three-cylinder motorcycles: this three-pack is an ideal service quantity where NGK specifies one CR9EIX per cylinder.
- Verified Triumph examples: Trident/Tiger Sport/Daytona 660, selected Daytona/Street Triple 675, Tiger 800, Tiger 900, and selected 955 triples are covered in the model-specific draft listings created with this export.
Fitment confidence: High for the plug identity/specification; vehicle fitment must be checked by exact model/year.
Spark-gap note: The correct installed gap is application-specific. Verified Triumph CR9EIX applications below commonly use 0.7 mm, while some 955 applications use 0.6 mm.
Important: CR9EIX is not interchangeable with every plug that shares a 10 mm thread. Use CR9EIX / stock 3521 as the compatibility key.
Manufacturer / Cross-References
- NGK CR9EIX – primary plug code
- NGK 3521 – NGK stock / manufacturer number
- NGK CR9EK / stock 4548 – standard NGK plug used on many of the verified Triumph three-cylinder applications below; CR9EIX is the NGK advanced iridium option
Vehicle manufacturers may assign their own service part numbers, but CR9EIX / 3521 is the key manufacturer identification for this genuine NGK product.
Before Ordering
- Check the existing spark-plug code or the NGK/Niterra application finder for your exact model and year.
- Do not order purely by engine capacity: motorcycles with the same capacity can use different heat ranges, reach, electrode styles or factory gaps.
- This listing contains three plugs. Confirm your engine requires three if buying a complete service set.
- Do not substitute CR9EIX for CR9EIA-9, CR8EIX, DPR8EIX-9 or other visually similar NGK plugs unless the manufacturer/application data explicitly permits it.
Fitting Note
Install spark plugs into a cool cylinder head using the correct tightening method for the engine manufacturer. Start the plug by hand to avoid cross-threading, and do not alter the factory electrode position unless the vehicle specification specifically requires a gap check/adjustment.
Delivery & Returns
- Free UK delivery with an estimated 2–3 working-day service
- 30-day returns, subject to the plugs remaining unused and in resalable condition