NGK BR4-LM Spark Plug (Stock No. 4133)
A reliable, resistor-type spark plug for many small engines. It delivers consistent ignition, helps reduce radio interference, and resists fouling for easier starts and smoother running. Ideal for lawn and garden equipment, generators, and other small petrol engines where BR4-LM is specified.
Use this part if your engine or manual calls for NGK BR4-LM. If unsure, use the site’s vehicle lookup or check the Vehicle Fitment tab.
| Part number | BR4-LM |
| NGK stock number | 4133 |
| GTIN | 087295141335 |
| Category | 686 – Spark Plug |
| Type | Resistor spark plug |
| Thread diameter | 14 mm |
| Thread pitch | 1.25 |
| Hex size | 20.8 mm (13/16 in) |
| Seat type | Flat seat with gasket |
| Reach (thread length) | 9.5 mm (3/8 in) |
| Heat range | 4 (NGK scale) |
| Centre electrode | Copper core, nickel alloy |
| Ground electrode | Nickel alloy |
| Resistor value | Approx. 5 k? |
| Factory gap | Approx. 0.7 mm (check and set to engine spec) |
| Terminal | Solid terminal |
- Improves cold starts and reduces misfires.
- Resistor design cuts electrical noise that can affect ignition modules and radios.
- Durable nickel electrodes for reliable performance over many hours of use.
Always confirm thread size, reach, and heat range match your engine’s specification before installation.
The price displayed is for a single plug, please add the desired amount to your basket.


