Small Engine
Briggs & Stratton 550ex Series
4-Stroke
The Briggs & Stratton 550EX is a 159cc <!-- verify: briggsandstratton.com --> 4-stroke overhead-valve engine used in upper entry-level consumer push mowers. The EX designation indicates an enhanced engine series with ReadyStart. It uses a Walbro or Nikki carburetor <!-- verify: briggsandstratton.com --> and a Champion RC12YC spark plug. At this displacement, the 550EX handles medium-density residential turf reliably. Annual maintenance: oil change (SAE 30 or 10W-30), air filter replacement, and spark plug inspection. The carburetor diaphragm and main jet are the primary fuel system service points. The most common engine on mid-range consumer push mowers sold at home improvement stores.
Briggs & Stratton 550ex Series quick specs
- Equipment
- Small Engine · 4-Stroke
- Covered Parts
- Spark Plug, Air Filter, Carburetor, Primer Bulb, Fuel Filter
- OEM References
- 5
- Model Family
- 450e Series, 500e Series, 550ex Series, 625ex Series, 675ex Series
ℹ See also: 450e Series, 500e Series, 625ex Series, 675ex Series — parts are often interchangeable within this family.
Spark Plug
OEM796112S(0.030" gap)Powers mid-range push mowers including Troy-Bilt TB110, TB130, and Craftsman M105 with 140cc engines
| Brand | Part # | |
|---|---|---|
| Champion | RC12YC | Buy on Amazon → |
| NGK | BPR5ES | Buy on Amazon → |
Air Filter
OEM593260Paper cartridge element; replaces 798452 and 334404. Fits 09P702 series engines. Pre-cleaner foam sold separately.
| Brand | Part # | |
|---|---|---|
| Stens | 100-959 | Buy on Amazon → |
Carburetor
OEM799584For 09P702 series 140cc engines. Also replaces 592361, 594057, 594058, 594529. Used on Troy-Bilt TB110, TB200.
| Brand | Part # | |
|---|---|---|
| Briggs & Stratton | 594058 | Buy on Amazon → |
Primer Bulb
OEM694394Fits all 450–675 series Briggs & Stratton small engines. DIY packaged version is 5084K.
| Brand | Part # | |
|---|---|---|
| Stens | 120-730 | Buy on Amazon → |
Fuel Filter
OEM298090S150-micron inline fuel filter for 1/4" fuel line; for engines without a fuel pump. DIY packaged version is 5018K.
| Brand | Part # | |
|---|---|---|
| Stens | 120-436 | Buy on Amazon → |