Briggs & Stratton Pistons & Piston Rings
Briggs & Stratton pistons and piston rings form the compression seal within small engine cylinders, converting combustion pressure into mechanical power. The engine piston features ring grooves holding compression rings that seal against cylinder walls and oil control rings that regulate lubrication. Lawn mower engine piston rings expand outward using spring tension, maintaining contact with the cylinder bore throughout operation. Chrome-plated rings suit aluminum bore engines while standard rings work with cast iron sleeves. Ring end gaps allow thermal expansion during operation. Worn piston rings cause blue smoke, oil consumption, and loss of compression. We hold Briggs & Stratton pistons and piston rings in stock and sell worldwide.
Available Briggs & Stratton Pistons & Piston Rings
Lock Piston Pin
698469
Briggs & Stratton
£5.15
In Stock
Piston Assembly
590404
Briggs & Stratton
£55.05
In Stock
Piston Assembly
391288
Briggs & Stratton
£127.60
Available
Piston Assy 020
499958
Briggs & Stratton
£127.60
Available
Piston Assembly
791786
Briggs & Stratton
£91.10
Available
Piston Assembly
791791
Briggs & Stratton
£116.00
Available
Piston Assembly
799063
Briggs & Stratton
£66.75
Available
Piston Assembly
597230
Briggs & Stratton
£60.05
Available
Pin Piston
84002062
Briggs & Stratton
£9.00
Available
Piston Assembly
298905
Briggs & Stratton
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Seal O Ring
710072
Briggs & Stratton
£6.20
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Spring Rewind
490179
Briggs & Stratton
£17.05
View More
Frequently Asked Questions
What are the symptoms of worn piston rings?
Blue smoke from the exhaust indicates oil burning past worn rings into the combustion chamber. Excessive oil consumption requiring frequent top-ups between oil changes confirms ring wear. Loss of power and difficulty starting result from reduced compression as rings no longer seal properly. Oil-fouled spark plugs with heavy carbon buildup appear when rings allow oil into cylinders. Engines may run smoothly but produce continuous smoke clouds, especially under load or acceleration. Compression testing shows readings below 80 PSI indicating severe ring wear requiring replacement.
How do you measure piston ring end gap correctly?
Push the ring squarely into the cylinder bore using the piston crown to ensure proper alignment. Use feeler gauges to measure the gap between ring ends—typical specifications are 0.007-0.020 inches for compression rings and up to 0.035 inches for oil control rings. Check gaps at multiple depths in the bore to verify cylinder wear. Excessive gaps beyond specifications indicate worn cylinder bores requiring oversized rings. New rings showing proper gap in a worn cylinder won't seal adequately—cylinder must be within 0.005 inches of standard size for chrome rings.
What's the difference between standard and oversize piston rings?
Standard rings fit cylinders at original factory bore diameter with minimal wear. Oversize rings (0.010", 0.020", 0.030") accommodate cylinders bored out to compensate for excessive wear or scoring. Check piston crown for oversize markings if unsure—previous rebuilds typically stamp the oversize dimension. Measure cylinder bore with telescoping gauges or inside micrometers to determine required ring size. Installing standard rings in worn oversized cylinders causes excessive blow-by and oil consumption. Briggs does not recommend honing aluminum cylinders—use chrome ring sets for cylinders worn up to 0.005 inches oversize.
Which way do piston rings install on the piston?
The top compression ring has an inside bevel or chamfer facing upward toward the piston crown. The middle ring features an outer scraper groove facing downward toward the crankcase. Oil control rings with two rails install with the expander spring between them. Any dot or mark stamped on rings always faces upward. Stagger ring end gaps 120-180 degrees apart—never align gaps as this allows compression loss. Use a ring expander tool to prevent breaking rings during installation. Oil all rings and grooves before installation to prevent initial startup scuffing.
Should you replace just rings or the entire piston?
Replace rings only if the piston shows no scoring, cracks, or excessive wear in ring grooves. Worn ring grooves with excessive side clearance prevent new rings from sealing properly. Check piston skirt for scuffing or aluminum transfer from cylinder contact. Measure piston-to-cylinder clearance—excessive clearance causes piston slap and oil consumption regardless of new rings. If cylinder requires boring oversized, install matching oversized piston and rings together. For engines with low hours showing ring failure, inspect for causes like dirt ingestion through damaged air filters before reassembly.