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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.

What this page covers

This page covers the Briggs & Stratton 450e Series 4-Stroke small engine.

Recorded annual maintenance parts: Spark Plug, Air Filter, Primer Bulb, Fuel Filter.

Reviewed spark-plug result: Champion RC12YC or NGK BPR5ES; 0.030 inch gap.

Evidence: explicit provenance is recorded (Aftermarket-confirmed; reviewed 2026-05-21).

Check before searching Amazon

Powers entry-level push mowers including Craftsman 140, Troy-Bilt TB110

Review annual maintenance parts
Verify before ordering: Fitment can vary by serial number, production date, region, and sub-model. Match the OEM number and physical dimensions before ordering.

Annual Maintenance Parts

These are individual maintenance components already present in this model record. No combined product claim is made.

Ignition

Spark Plug

OEM number
491055S
Specification / dimensions
0.030 inch gap
Evidence status
Medium confidence · Aftermarket catalog · 2026-05-21
Variant / exclusion warning
Powers entry-level push mowers including Craftsman 140, Troy-Bilt TB110

Air intake

Air Filter

OEM number
798452
Specification / dimensions
Not recorded
Evidence status
Medium confidence · Aftermarket catalog · 2026-05-21
Variant / exclusion warning
Also sold as 593260; fits 09P702, 092J0B, and 093J02 engines

Fuel delivery

Primer Bulb

OEM number
694394
Specification / dimensions
Not recorded
Evidence status
Medium confidence · Aftermarket catalog · 2026-05-21
Variant / exclusion warning
Also sold as 5084K; replaces 494408

Fuel Filter

OEM number
493629
Specification / dimensions
Not recorded
Evidence status
Medium confidence · Aftermarket catalog · 2026-05-21
Variant / exclusion warning
1/4" inline fuel filter; also replaces 691035

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
ℹ See also: 500e Series, 550ex Series — verify each model and part independently; family membership does not establish fitment.

Quick Fitment

Part TypeOEM / SpecCommon OptionConfidence
Spark Plug491055SChampion RC12YCMedium · 2026-05-21
Air Filter798452Stens 102-851Medium · 2026-05-21
Carburetor799584Stens 520-042Medium · 2026-05-21
Primer Bulb694394Stens 120-178Medium · 2026-05-21
Fuel Filter493629Stens 120-158Medium · 2026-05-21

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.

Named part options

Cross-check named parts such as Champion RC12YC (spark plug), Stens 102-851 (air filter), Stens 520-042 (carburetor) against the OEM number, identity label, and dimensions.

Best if replacing fuel system

Compare the carburetor, primer bulb, fuel filter together so line routing, bulb size, filter style, and carburetor connections match.

FAQ

Does this fit 500e Series or 550ex Series? 500e Series, 550ex Series are listed in the same model family. That relationship does not establish interchangeable parts; verify each OEM number, serial range, and physical detail separately.

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.

Related Repair Guides

Briggs 450e Won't Prime: Diagnosis and 594058 ChecksDiagnose a Briggs 450e no-prime or stall symptom before replacing the carburetor, then verify 594058 identity and engine-model fitment separately.Where to Find the Engine Code on Briggs EnginesHow to locate and use Briggs & Stratton engine model, type, and code numbers before ordering mower service parts.

Spark Plug

OEM491055SConfidence: Medium · Source: Aftermarket catalog
Reviewed
2026-05-21
Dimensions
0.030 inch gap
Variant notes
Powers entry-level push mowers including Craftsman 140, Troy-Bilt TB110
BrandPart #Identity
ChampionRC12YCNot classified
Search Amazon for Champion RC12YCAmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

NGKBPR5ESNot classified
Search Amazon for NGK BPR5ESAmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

Air Filter

OEM798452Confidence: Medium · Source: Aftermarket catalog
Reviewed
2026-05-21
Variant notes
Also sold as 593260; fits 09P702, 092J0B, and 093J02 engines
BrandPart #Identity
Stens102-851Not classified
Search Amazon for Stens 102-851AmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

Carburetor

OEM799584Confidence: Medium · Source: Aftermarket catalog
Reviewed
2026-05-21
Variant notes
Float-type carb for 09P702 engine; replaces 594058
BrandPart #Identity
Stens520-042Not classified
Search Amazon for Stens 520-042AmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

Primer Bulb

OEM694394Confidence: Medium · Source: Aftermarket catalog
Reviewed
2026-05-21
Variant notes
Also sold as 5084K; replaces 494408
BrandPart #Identity
Stens120-178Not classified
Search Amazon for Stens 120-178AmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.

Fuel Filter

OEM493629Confidence: Medium · Source: Aftermarket catalog
Reviewed
2026-05-21
Variant notes
1/4" inline fuel filter; also replaces 691035
BrandPart #Identity
Stens120-158Not classified
Search Amazon for Stens 120-158AmazonAffiliate link

As an Amazon Associate, WhichPartFits may earn from qualifying purchases. Match the OEM number, dimensions, and model variant before buying.