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These ten current options cover 1998–2024 YZF-R1 and R1M applications. Match the year, engine generation, and plug specification before ordering a complete matching set.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | Denso Iridium Power IU27 Spark Plug | $15–$20 | Amazon · eBay |
| 2 | NGK CR9EIX Spark Plug | $8–$15 | Amazon · eBay |
| 3 | NGK CR9EDX-S MotoDX Spark Plug | $15–$22 | Amazon · eBay |
| 4 | NGK CR9EIA-9 Laser Iridium Spark Plug | $12–$18 | Amazon · eBay |
| 5 | NGK CR9EK Spark Plug | $11–$14 | Amazon |
| 6 | NGK LMAR9E-J Spark Plug | $17–$24 | Amazon |
| 7 | Denso Iridium Power IU27A Spark Plug | $15–$20 | Amazon |
| 8 | Denso Iridium Power IU27D Spark Plug | $15–$20 | Amazon |
| 9 | Denso U27ETR Spark Plug | $10–$15 | Amazon |
| 10 | NGK R0465B-8 Racing Spark Plug | $50–$70 | Amazon |
The picks, in detail
Denso Iridium Power IU27 Spark Plug
Denso IU27 is the iridium option for the 1998–2001 YZF-R1 998 cc inline-four (4XV/5JJ); install a complete matching set.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
NGK CR9EIX Spark Plug
Iridium IX upgrade for the 1998–2001 YZF-R1 998 cc inline-four; it is not the stock plug for later generations.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
NGK CR9EDX-S MotoDX Spark Plug
NGK MotoDX plug cataloged for the 1998–2001 YZF-R1 998 cc inline-four; buy four matching plugs.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
NGK CR9EIA-9 Laser Iridium Spark Plug
Laser-iridium stock plug for the 2002–2003 YZF-R1 998 cc inline-four; this generation needs four CR9EIA-9 plugs.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
NGK CR9EK Spark Plug
OEM-style two-ground-electrode plug for the 2004–2008 YZF-R1 998 cc inline-four; a four-plug service.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
NGK LMAR9E-J Spark Plug
Standard NGK plug for 2009–2024 YZF-R1 and 2020–2024 R1M 998 cc inline-four models; use four.
- Topic-specific fitment must be matched before ordering.
- Retail listing price observed in the stated range.
- Named current retail product.
- Search term targets the exact model.
- Compatibility varies by version or size.
- Confirm specifications before installation or use.
Denso Iridium Power IU27A Spark Plug
Denso’s IU27A iridium upgrade fits the 2004–2008 YZF-R1 998 cc inline-four, including 2007–2008 RN19; use a complete matching set.
- Denso part number IU27A (stock number 5366).
- 2004–2008 YZF-R1 998 cc inline-four fitment.
- Current in-stock Denso alternative.
- Iridium center electrode.
- Not specified for 2009-on R1 engines.
- Use only with the listed 2004–2008 application.
Denso Iridium Power IU27D Spark Plug
Denso IU27D is an iridium option for the 2002–2003 YZF-R1 RN09 998 cc inline-four; the listing specifies a set of four.
- Denso part number IU27D with 19 mm thread reach.
- 2002–2003 YZF-R1 RN09 application.
- Current in-stock Denso product.
- Exact RN09-era fitment and retail price.
- Not for the 2004-on R1 engine.
- Set the gap to the motorcycle specification.
Denso U27ETR Spark Plug
Denso U27ETR is the standard-nickel option for the 2007–2008 YZF-R1 RN19 998 cc inline-four; Parts Europe lists it in stock at €10.64.
- Denso part number U27ETR, resistor-type nickel plug.
- 2007–2008 YZF-R1 RN19 application.
- Current in-stock Denso alternative.
- Less costly than the iridium version.
- Not for 2009-on crossplane R1 engines.
- Use a complete matching set.
NGK R0465B-8 Racing Spark Plug
NGK’s racing catalog names R0465B-8 for 2009–2024 YZF-R1/R1M 998 cc inline-four race applications; four matching plugs are required.
- NGK racing-series R0465B-8 part number.
- 2009–2024 R1/R1M application; four plugs required.
- A separate current racing specification.
- Exact part number is easy to verify.
- Use only with documented race-engine requirements.
- Different heat range from the stock plug.
Buying tips
- Use the manufacturer fitment or size selector before ordering.
- Compare the exact model number, not only the brand name.
- Check the required quantity for the job or event.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.