The Honda 98079-55155 Spark Plug (W16EPR-U11) is a genuine OEM ignition component designed for a wide range of Honda generators, welder generators, horizontal shaft engines, and lawn and multi-purpose tractors, including the GX340, GX640, EB5000, EM5000, EW171, and EXW171, among others. As a factory-original part, this spark plug is matched to the exact heat range and electrode gap Honda specifies for consistent ignition across every application it serves. Verify your model and serial number against the fitment table before ordering, as Honda updates part numbers at production breaks and the W16EPR-U11 designation identifies this specific plug grade. DHS Equipment supplies this part direct from Honda's OEM catalog, so you receive the correct specification every time.
Key Features
- OEM-Correct Heat Range — the W16EPR-U11 designation specifies the exact thermal rating Honda engineers selected for these engines and machines, ensuring the plug runs at the right operating temperature to burn cleanly without fouling or pre-ignition
- Direct Drop-In Replacement — thread pitch, reach, and hex size match the original, allowing straightforward installation with no modifications to the cylinder head or plug boot
- Broad Fitment Across Honda Lines — listed for GX340 and GX640 horizontal shaft engines, EB5000, EG5000, EM5000, and EX4500 generators, EW171 and EXW171 welder generators, and H4518, H5013, H5518, and RT5000 lawn and multi-purpose tractors
- Check Your Serial Number — Honda supersedes spark plug specifications at production breaks; confirm your unit's serial number against the fitment table to ensure this is the correct plug for your specific machine
- Ignition Consistency — a correctly rated plug fires reliably at every start and sustains a clean spark under load; a fouled or mismatched plug causes hard starting, rough running, and elevated fuel consumption
A spark plug is the ignition source for a four-stroke engine, generating the electrical arc that ignites the compressed air-fuel mixture inside the combustion chamber. The plug's heat range — encoded in the W16EPR-U11 designation — determines how efficiently it transfers heat away from the electrode tip; too cold and the tip soots up, too hot and it risks pre-ignition damage. When a spark plug wears, cracks, or becomes fouled with carbon or oil deposits, the engine becomes difficult to start, runs unevenly, or misfires under load, making timely replacement one of the simplest and most effective tune-up steps available.
Part Details
| Part Number | 98079-55155 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Spark Plug (W16EPR-U11) |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Generator | EB5000, EG5000, EM5000, EX4500 | 1000001-1253117 |
| Horizontal Shaft Engine | GX340, GX640 | All |
| Lawn Tractor | H4518 | All |
| Multi-Purpose Tractor | H5013, H5518, RT5000 | All |
| Welder Generator | EW171, EXW171 | 1000001-1253117 |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
