Small Engine
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.
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).
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Powers entry-level push mowers including Craftsman 140, Troy-Bilt TB110
These are individual maintenance components already present in this model record. No combined product claim is made.
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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.
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
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.
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.
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