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This one really is narrow, for a specific reason: Honda specifies a single NGK iridium family for the CBR600RR’s high-revving inline-four, and the heat range isn’t optional on an engine that spends most of its life above 10,000 RPM. The real variation is the model-year split — standard vs. ABS models take different part numbers — plus a colder-range option for track use, and a cross-referenced Denso equivalent for buyers who prefer to shop off-brand.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | NGK IMR9C-9HES (NGK 5766) | $11.86–$16 each | Amazon · eBay |
| 2 | NGK IMR9E-9HES (NGK 7556) | $13–$16.68 each | Amazon · eBay |
| 3 | NGK IMR9C-9H (NGK 6777) | $12.44 each | Amazon · eBay |
| 4 | Denso Iridium IK27 (5312) | $42.69 (set of 4, ~$10.67 each) | Amazon · eBay |
The picks, in detail
NGK IMR9C-9HES (NGK 5766)
The standard-heat-range plug Honda specifies for the 2003–2012 non-ABS CBR600RR — the correct default for street riding.
- Laser-welded fine-wire iridium tip
- Pre-gapped from the factory
- Direct Honda-specified fitment
- Consistent spark at high RPM
- Don’t attempt to re-gap with a standard blade tool — the fine tip bends easily
NGK IMR9E-9HES (NGK 7556)
The correct part for ABS-equipped CBR600RR models (2009–2017) — a different plug family (E vs. C tip design) than the non-ABS bike takes.
- Trivalent metal-plated shell for anti-corrosion
- Platinum disc on the ground electrode
- Confirmed correct fitment for ABS model years
- Easy to order the wrong C/E variant if you don’t check your model year and ABS status first
NGK IMR9C-9H (NGK 6777)
One heat range colder than the stock 9HES — a track-day option for riders running the bike harder and longer than street use.
- Laser-welded iridium center electrode
- Colder heat range for sustained high load
- Better fouling resistance under track conditions
- Not the right pick for normal street riding — running too cold a plug on the street can cause fouling
Denso Iridium IK27 (5312)
Marketed explicitly as a “heat range 9 equivalent” to the NGK 9-series plugs above — a cross-brand alternative for buyers who want a non-NGK option.
- Iridium center electrode
- Sold as a set of 4
- Real alternative to NGK at a similar heat range
- Not Honda’s specified part — NGK remains the OEM-endorsed choice
Buying tips
- Check your model year and whether your CBR600RR has ABS before ordering — non-ABS bikes (2003–2012) and ABS bikes (2009–2017) take different NGK part numbers.
- Iridium plugs on this bike typically arrive pre-gapped. Don’t use a standard blade-style gapping tool on the fine-wire tip — use a wire-style feeler gauge if you must check it.
- The colder IMR9C-9H is a track/performance option, not a street upgrade — stick with the stock-heat-range 9HES for normal riding.
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