NGK BR9EIX Iridium IX Spark Plug (Stock No. 3981)
The NGK BR9EIX is a cold heat-range iridium spark plug designed for reliable ignition under hard use. The fine-wire iridium tip needs less voltage to spark, which helps cold starts, cleaner running, and steady performance at high rpm. It also resists wear better than standard copper plugs, so it keeps its gap and performance for longer.
Suitable for many high-performance 2-stroke motorcycle, ATV and marine engines that specify an NGK BR9 plug. Always confirm fitment and heat range with the Vehicle Fitment tab or the site’s vehicle lookup.
- Fine-wire iridium centre electrode for a strong, consistent spark
- Resistor type to reduce electrical noise that can affect ECUs
- Cold heat range (9) for sustained high-load running
| Part number | BR9EIX |
| NGK stock number | 3981 |
| Category | 686 – Spark Plug |
| GTIN | 087295139813 |
| Thread diameter | 14 mm |
| Thread pitch | 1.25 |
| Reach (thread length) | 19 mm |
| Hex size | 20.8 mm (13/16 in) |
| Seat type | Flat seat with gasket |
| Heat range | 9 (cold) |
| Resistor | Yes |
| Centre electrode | Iridium, fine-wire approx. 0.6 mm |
| Ground electrode | Nickel alloy |
| Factory gap | 0.8 mm (check and adjust to your spec) |
Important: Use the correct heat range and gap for your engine. Check the Vehicle Fitment tab or use the site’s lookup before ordering.
The price displayed is for a single plug, please add the desired amount to your basket.


