The fuel injector sealing interface on high-output Mercury Racing two-stroke engines is among the most technically demanding locations for elastomer performance in marine applications.
With the discontinuation of Mercury’s original lower side-injector seal (P/N 26-94219), a key sealing element was suddenly absent from the supply chain—jeopardizing the longevity and performance of motors that depend on absolute integrity at the injector-to-manifold interface.
These include the Mercury 2.0 Liter F1, 2.4 Liter side-injected Bridgeport, 2.5 Liter EFI Offshore, 2.5 ROS (Race Offshore), 260 EFI, 280 ROS (Race Offshore), 300 Drag, and the S3000 race engines.
Unlike general-purpose O-rings or off-the-shelf gaskets, this particular 94219 lower seal maintains critical fuel rail pressure and prevents ambient air ingestion around the injector base. Improper sealing at this point leads to unstable mixture formation, especially under transient load and wide-open throttle. This is not a theoretical concern—lean-outs, injector misfires, and EGT asymmetry are real outcomes seen by tuners working with compromised sealing interfaces.
Replicating the Mercury Racing Seal with OEM Victor Reinz
After extensive testing of aftermarket substitutes—none of which reliably duplicated the performance of the original—Buckshot Racing pursued a direct solution. Rather than reverse-engineer a failed component or use dimensional guesswork, the team replicated the original seal by working with Victor Reinz, a division of Dana Corporation and Mercury Racing’s original supplier.
This collaboration ensured that the geometry, elastomer compound, and sealing characteristics matched the exact form and function Mercury intended.
Replicating the OEM design required access to original tooling references, historical durometer specifications, and knowledge of the intended compressive set and thermal deformation profile.
The result is the Buckshot Racing #77 Lower Fuel Injector Seal—a part that is dimensionally and chemically faithful to the OEM seal, produced using modern quality controls and updated materials for current race-fuel compatibility.
Advanced Material Specification and Function
This seal is molded from a high-temperature fluorocarbon elastomer optimized for marine race applications. The material formulation offers resistance to swelling, compression set, and chemical degradation from ethanol, MTBE, toluene, and high-oxygen content fuels.
The seals (26-94219) are exposed to heat-soak conditions near 150–180°C during extended wide-open-throttle operation, especially on the 2.5 EFI Offshore and 280 ROS, where injector body temps spike under cowl ventilation constraints.
The compound’s low permeability ensures that the seal resists fuel vapor intrusion and retains structural integrity across multiple thermal cycles. With a hardness carefully matched to Mercury’s injector rail tolerance stack-up, the seal provides consistent crush and surface contact without inducing overcompression or extrusion, which is critical in high-RPM race motors running at 7,500–11,000 RPM.
Manufactured to IATF 16949 Standards
Victor Reinz manufactures this component under IATF 16949-certified processes—a global automotive quality standard ensuring traceability, process control, and rigorous validation. This includes tensile strength verification, elongation tolerance, low- and high-temp aging, and leak path evaluation.
The seal is CNC-tooled and cavity-molded with micro-tolerance flash control to eliminate burrs that could affect seating. After molding, seals are post-cured in a controlled oven cycle to remove volatile residues that can migrate into fuel systems and degrade injector performance.
The manufacturing process includes in-line optical dimensional inspection to ensure that every batch conforms to radial and axial thickness tolerances within hundredths of a millimeter. Compression-set testing is performed on samples across the batch run to confirm long-term seal retention.
Real-World Performance in Mercury Race Motors
The seal’s application spans nearly the full spectrum of Mercury’s high-output 2-stroke performance engines. The 2.0 Liter F1 and 2.4 Liter Bridgeport—both used in early tunnel boat racing—demand precise fueling and consistent vacuum under rapid throttle transitions.
The 2.5 EFI Offshore and ROS variants (Race Offshore), often used in endurance formats, require fuel system integrity over prolonged thermal cycles. Similarly, engines like the 260 EFI, 280 ROS, 300 Drag, and S3000 operate at extreme volumetric efficiency where a single air leak can translate into cylinder-to-cylinder imbalances.
Sealing failure in any of these motors can result in elevated exhaust gas temperatures, lean mixture-induced detonation, or even piston dome failure. By returning the injector rail to its original design intent, the Buckshot Racing #77 helps preserve optimal injector flow consistency, avoids fuel rail pressure losses, and reduces the risk of post-shutdown vapor lock.
The Buckshot Racing #77 Lower Fuel Injector Seal is not an aftermarket workaround—it is a faithful replication of the original Mercury Racing part, produced in cooperation with the original supplier, Victor Reinz.
By delivering the correct compound, geometry, and quality control, it restores a critical component to high-performance Mercury 2-stroke platforms. For engine builders and racers maintaining the legacy of the 2.0L F1, 2.4 Bridgeport, 2.5 EFI Offshore, 2.5 ROS (Race Offshore), 260 EFI, 280 ROS (Race Offshore), 300 Drag, and S3000 outboards, this seal ensures that fuel delivery and engine reliability remain uncompromised.
Includes 6 (six) Lower Seals (26-94219-77) for $24, Buy 3 Packs, Save $15
For technical questions, contact Mike at mike@buckshotracing77.com or call (714) 697-1716.