Briggs & Stratton Balance Shafts
Briggs & Stratton balance shafts and counterbalance systems reduce engine vibration for smoother operation across lawn mowers, generators, and outdoor power equipment. These rotating components counteract reciprocating forces from pistons to minimize shaking and extend equipment life. Balance shaft assemblies include gears, bearings, and timing marks requiring precise alignment during installation. Failed balance shafts cause excessive vibration, unusual knocking noises, and potential damage to engine mounts and components. We hold balance shafts and counterbalance assemblies in stock for various Briggs & Stratton engine models and sell worldwide, ensuring genuine OEM parts for reliable vibration control.
Available Briggs & Stratton Balance Shafts
Fuel Tank
291488
Briggs & Stratton
£107.15
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Fuel Tank
699392
Briggs & Stratton
£80.05
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Seal O Ring
710072
Briggs & Stratton
£6.20
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Spring Rewind
490179
Briggs & Stratton
£17.05
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Battery Cover
7028990YP
Briggs & Stratton
£22.70
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V Belt
5106125
Briggs & Stratton
£36.31
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Diaphragm Carburetor
270026
Briggs & Stratton
£4.65
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Carburetor Diaphragm
272538S
Briggs & Stratton
£5.05
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Valve Exhaust
211119S
Briggs & Stratton
£22.60
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Keeper Valve
494553
Briggs & Stratton
£6.10
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Spring Governor
793342
Briggs & Stratton
£6.50
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Spline Starter
799420
Briggs & Stratton
£20.17
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Frequently Asked Questions
Can I run my engine without balance shafts if they fail?
While some engines can technically run without balance shafts, it's not recommended for regular use. Removing balance shafts causes significantly increased vibration, which accelerates wear on bearings, loosens fasteners, damages engine mounts, and creates operator discomfort. For lawn mowers, the blade weight helps dampen some vibration, but horizontal shaft engines on generators or pressure washers will shake excessively. If removing balance shafts, you must properly plug oil passages to maintain oil pressure and install blocking plates or covers. This modification voids warranties and may reduce engine lifespan substantially.
What causes balance shaft bearings to wear out prematurely?
Common causes include running the engine with insufficient oil, which starves the balance shaft bearings of lubrication, contaminated oil with metal particles or dirt accelerating bearing wear, improper timing alignment creating excessive stress on components, loose or missing mounting bolts allowing excessive play, and overfilling oil which can cause foaming and reduced lubrication effectiveness. Extended periods of high-rpm operation, especially under heavy load, also accelerate wear. Regular oil changes with the correct grade, maintaining proper oil levels, and keeping the crankcase breather clean all help maximize balance shaft bearing life.
What do balance shafts actually do in a Briggs & Stratton engine?
Balance shafts are weighted gears rotating opposite to the crankshaft to cancel vibrations created by the piston moving up and down. In single-cylinder engines, the reciprocating motion of the piston creates lateral forces that cause the engine to shake. Balance shafts spin at precise speeds with their heavier side positioned opposite the crankshaft counterweight at specific rotation points. This creates opposing forces that neutralize vibration, resulting in smoother operation, reduced wear on engine mounts and bolts, less operator fatigue, and longer equipment life.
What are the warning signs that balance shafts are failing?
Excessive engine vibration is the primary symptom, especially noticeable when the engine is running without load. Other signs include unusual knocking or rattling noises from the lower engine area that change with engine speed, engine shaking violently enough to loosen bolts or damage mounts, equipment vibrating abnormally during operation, and oil pressure fluctuations if balance shaft bearings are worn. If your previously smooth-running engine suddenly develops a persistent shake or knocking sound, inspect the balance shaft system before continuing operation to prevent catastrophic damage.
How do I know if my balance shaft timing is correct during reassembly?
Balance shaft timing is critical and uses alignment marks stamped on the gears. During installation, align the timing marks on the balance shaft gears with corresponding marks on the crankshaft gear exactly as specified in your engine's service manual. Incorrect timing results in increased vibration rather than reduced vibration, defeating the entire purpose. The shafts must mesh at precise positions to rotate in sync with piston movement. Use a paint pen to mark positions before disassembly if factory marks are worn. Never force gears together, and hand-rotate the crankshaft several revolutions after assembly to verify smooth operation before reinstalling the engine cover.