Small Engine
Briggs & Stratton 450e Series
4-Stroke
The Briggs & Stratton 450e is a 125cc 4-stroke overhead-valve engine used in entry-level push mowers from Craftsman, Troy-Bilt, and Toro. It features ReadyStart primer-free cold-starting. The 450e uses a Walbro or Nikki carburetor and accepts a Champion RC12YC or equivalent spark plug. Routine maintenance items are the oil (SAE 10W-30), air filter, and spark plug, replaced annually or every 50 hours. The 450e is the entry point to B&S's modern consumer engine lineup and one of the most commonly serviced push mower engines at small engine shops.
Briggs & Stratton 450e Series quick specs
- Equipment
- Small Engine · 4-Stroke
- Covered Parts
- Spark Plug, Air Filter, Carburetor, Primer Bulb, Fuel Filter
- OEM References
- 491055S, 798452, 799584, 694394, 493629
- Model Family
- 450e Series, 500e Series, 550ex Series
- Last Reviewed
- 2026-05-21
- Data Confidence
- Aftermarket-confirmed
- Sources Consulted
- Briggs & Stratton 450e parts references, Aftermarket catalog cross-references, Retailer fitment listings
Quick Fitment
| Part Type | OEM / Spec | Common Option | Confidence |
|---|---|---|---|
| Spark Plug | 491055S | Champion RC12YC | Medium · 2026-05-21 |
| Air Filter | 798452 | Stens 102-851 | Medium · 2026-05-21 |
| Carburetor | 799584 | Stens 520-042 | Medium · 2026-05-21 |
| Primer Bulb | 694394 | Stens 120-178 | Medium · 2026-05-21 |
| Fuel Filter | 493629 | Stens 120-158 | Medium · 2026-05-21 |
Tune-Up Kit
Common service bundle: spark plug, air filter, carburetor, primer bulb, fuel filter.
Maintenance Interval
Inspect filters and fuel lines each season, replace spark plugs during annual service, and service carb/fuel-system parts when starting or idle symptoms appear.
Before You Buy
- Confirm the full model is Briggs & Stratton 450e Series, not just the family name.
- Check serial number, production date, and regional variant before ordering.
- Match the old OEM number stamped on the removed part when available.
- Compare dimensions, plug gap, thread, fuel line diameter, or chain pitch/gauge where applicable.
Common Mistakes
- Ordering from a family listing without checking the exact sub-model.
- Buying a kit that includes the headline part but wrong gaskets, lines, or bulb size.
- Choosing the wrong carburetor revision when multiple versions were used.
- Installing the correct plug number with the wrong gap.
Symptoms Map
Won't start
Spark plug, fuel filter, primer bulb, carburetor
Starts then dies
Fuel filter, fuel line kit, carburetor
Bogs under throttle
Air filter, carburetor, spark plug gap
Primer will not fill
Primer bulb, fuel line routing, in-tank filter
Replacement Options
Best OEM equivalent
Start with OEM references 491055S, 798452, 799584, 694394 and match the removed part before choosing a listing.
Common aftermarket option
Cross-check aftermarket listings such as Champion RC12YC (spark plug), Stens 102-851 (air filter), Stens 520-042 (carburetor) against the OEM number and dimensions.
Best for annual tune-up
Bundle spark plug, air filter, fuel filter when servicing the Briggs & Stratton 450e Series at the start of the season.
Best if replacing fuel system
Compare the carburetor, primer bulb, fuel filter together so line routing, bulb size, filter style, and carburetor connections match.
Best budget kit
Use kit listings only when every included part matches this model page; cheap kits often mix correct headline parts with wrong bulbs, lines, or gaskets.
FAQ
Does this fit 500e Series or 550ex Series? Parts may interchange with 500e Series, 550ex Series, but verify the serial range, OEM number, and physical part details before ordering.
Should I buy OEM or aftermarket parts for the Briggs & Stratton 450e Series? Use OEM when the part controls fuel metering, ignition, or safety. Aftermarket kits can be useful for routine filters, bulbs, plugs, and tune-up bundles when the OEM number and dimensions match.
How do I avoid ordering the wrong carburetor for the 450e Series? Match the carburetor number stamped on the removed unit, then compare linkage, choke setup, primer routing, gasket stack, and fuel-inlet direction.
What should I check before replacing fuel-system parts? Photograph the old fuel-line routing, match line diameter and filter style, and compare primer bulb size before buying a kit.
Related Repair Guides
Spark Plug
- Reviewed
- 2026-05-21
- Dimensions
- 0.030 inch gap
- Variant notes
- Powers entry-level push mowers including Craftsman 140, Troy-Bilt TB110
Air Filter
- Reviewed
- 2026-05-21
- Variant notes
- Also sold as 593260; fits 09P702, 092J0B, and 093J02 engines
| Brand | Part # | |
|---|---|---|
| Stens | 102-851 | Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying. |
Carburetor
- Reviewed
- 2026-05-21
- Variant notes
- Float-type carb for 09P702 engine; replaces 594058
| Brand | Part # | |
|---|---|---|
| Stens | 520-042 | Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying. |
Primer Bulb
- Reviewed
- 2026-05-21
- Variant notes
- Also sold as 5084K; replaces 494408
| Brand | Part # | |
|---|---|---|
| Stens | 120-178 | Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying. |
Fuel Filter
- Reviewed
- 2026-05-21
- Variant notes
- 1/4" inline fuel filter; also replaces 691035
| Brand | Part # | |
|---|---|---|
| Stens | 120-158 | Some links may be affiliate links. Match the OEM number, dimensions, and model variant before buying. |