For high performance boating enthusiasts and professional engine builders looking to restore the performance of their Mercury 2.4L V6 two-stroke chrome bore engines, the 2.4 Liter Chrome Bore Rings offered by Buckshot Racing #77 provide a the highest-quality replacement option for OEM part numbers 77876, 78996, 813011 and others.
 
Manufactured by RIKEN (RIK), a world leader in piston ring technology, these 2mm semi-keystone, molybdenum-coated rings offer advanced durability and performance benefits over standard factory replacements. With precise engineering and a specialized coating designed for chrome bore applications, these rings ensure proper sealing, reduced friction, and extended engine life.
 
One key feature of the Buckshot Racing #77 rings is their semi-keystone design, which provides several advantages over conventional rectangular rings.
 
The semi-keystone shape allows the ring to rotate slightly within the piston groove, helping to reduce carbon buildup and prevent ring sticking—a common issue in two-stroke engines running at high RPMs.
 
This design also promotes better sealing by maintaining consistent contact with the cylinder wall, ensuring optimal compression throughout the engine’s operating range.
 
The self-cleaning action of a semi-keystone ring improves long-term durability, making it especially beneficial in two-stroke applications where oil and combustion byproducts can cause buildup in the ring lands.
 
By incorporating this semi-keystone profile, these rings enhance engine reliability and performance longevity, particularly in high-output two-stroke marine engines like the Mercury 2.4L V6.
 
Honing Recommendations for Rebuilding Mercury 2.4L Chrome Bore Engines
 
When rebuilding a Mercury 2.4L V6 two-stroke engine, it is crucial to assess the condition of the chrome bore before installing new piston rings. Unlike traditional cast-iron or Nikasil-lined cylinders, chrome bores require a specific honing technique to ensure proper ring seating and optimal performance.
 
Should You Hone a Chrome Bore Before Installing These Rings?
 
If the bore is in good condition (no peeling, flaking, or deep scoring), a light honing or deglazing may be beneficial to help the new rings seat properly.
 
If the bore shows significant wear, flaking, or peeling, it may require re-plating or a sleeve replacement before proceeding with new rings.
 
What Type of Hone Should Be Used?
 
For chrome bore engines, traditional abrasive hones (such as ball hones or silicon carbide stones) should not be used, as they can damage the hard chrome surface. Instead, a flex-hone (brush hone) with fine-grit abrasive bristles (such as aluminum oxide or diamond-impregnated brushes) is recommended.
 
Recommended Hone Type: Flex-Hone or Brush Hone (specifically designed for chrome bores)
 
Grit Recommendation: 320-400 grit aluminum oxide or diamond-based brush hone
 
Honing Purpose: Lightly deglaze the surface to promote proper ring seating without removing significant material.
 
A crosshatch pattern is not required in chrome bores like it is in cast-iron cylinders. The goal is simply to clean the bore and remove any glazing without damaging the chrome plating. Over-honing can prematurely wear the chrome surface, reducing the engine’s longevity.
 
By using Buckshot Racing 2-4 Liter Chrome Bore Rings, builders and restorers can ensure proper sealing, improved oil retention, and extended ring life in their Mercury 2.4L V6 two-stroke engines.
 
The molybdenum-based coating provides excellent wear resistance, making it ideal for the high-RPM, high-load conditions that these engines experience.
 
The semi-keystone design further enhances performance by reducing carbon buildup, improving sealing consistency, and preventing ring sticking, all of which contribute to longer-lasting, high-efficiency operation.
 
By following proper honing recommendations and ensuring the bore is in good condition, these rings will provide optimal compression and peak engine efficiency, helping to bring classic Mercury 2.4L chrome bore engines back to their original power levels.
 
RIKEN is a globally recognized OEM and high-performance aftermarket piston ring manufacturer, supplying components to leading automotive, motorcycle, and marine engine manufacturers.
 
Their manufacturing facilities adhere to the highest quality standards, holding ISO 9001 (Quality Management System) and ISO/TS 16949 (Automotive Quality Management System) certifications. These certifications ensure that every piston ring meets strict dimensional tolerances, material integrity, and performance reliability.
 
RIKEN’s advanced metallurgical processes and precision coating technologies are designed to withstand the demands of high-performance two-stroke applications.
 
The molybdenum-based coating used on our 2.4 Liter Chrome Bore Rings enhances lubrication, wear resistance, and sealing properties, making these rings a perfect match for the Mercury 2.4L V6 standard chrome bore engine.
 
These rings cross-reference with Mercury part numbers 77876A12, 78996A12, 813011A12, and 39-813011A12, providing an exact match for builders looking to restore compression and performance.
 
Includes tweve (12) 2.4 Liter Chrome Bore Piston Rings (Standard Size Bores) the rebuild one V6 Powerhead.
 
For technical support feel free to contact Mike Hill directly at mike@buckshotracing77.com or call +1-714-697-1716.