The Buckshot Racing #77 High-Performance 8mm CDM Spark Plug Wire is designed for compatible 1993-2010 Mercury, Mariner, Force, and SportJet two-stroke engines equipped with CDM ignition.
Built as a heavier-duty replacement for aging factory ignition leads, this wire provides a fresh, reliable high-voltage connection between the CDM ignition module and spark plug.
The wire features a distinctive blue 8mm high-performance ignition cable with black protective spark plug boots and a bell boot on the female-insert coil side, making it easy to identify while providing additional insulation and physical protection in the harsh under-cowl environment.
It replaces common Mercury high-tension lead assemblies including 84-813706A56, 84-821945A61 and 857124A1 on compatible CDM applications.
Built for Mercury CDM Ignition Systems
Mercury's CDM, or Capacitor Discharge Module, ignition system combines the ignition electronics and coil function into individual modules mounted near each cylinder. From the CDM, the spark plug wire carries the high-voltage ignition output directly to the spark plug.
That short connection is easy to overlook, but it operates under constant heat, vibration, and electrical stress. As an original wire ages, the insulation can harden, the conductor can deteriorate, and the terminals inside the boots can corrode or loosen.
A weak high-tension lead can contribute to intermittent spark, hard starting, rough running, high-RPM misfire, or a cylinder that cuts in and out under load.
High-Performance 8mm Construction
The Buckshot Racing #77 replacement uses a larger 8mm ignition cable vs a smaller 7mm stock-style lead. The heavier insulation provides additional protection against heat, abrasion, and voltage leakage while maintaining the flexibility needed for proper routing around the powerhead.
The blue outer jacket gives the wire a clean performance appearance, while the black boots at both ends protect the terminal connections from moisture, contamination, and accidental contact with surrounding components.
This upgrade is intended to improve durability and serviceability. It does not create additional ignition energy; the CDM determines spark output. The purpose of the wire is to carry that available voltage to the spark plug consistently with minimal leakage or interruption.
1993-2010 Mercury, Mariner & Force Applications
This spark plug wire is intended for compatible 1993-2010 engines using Mercury-style CDM ignition and one of the listed OEM high-tension lead numbers.
Applications include numerous two-stroke Mercury and Mariner engines, including selected 40, 50, 60, 75, 90, 100, 115, and 125 HP models, along with larger V6 CDM applications that use the same plug-wire connection.
It also applies to selected later Force outboards that adopted Mercury ignition components and to compatible Mercury SportJet and JetDrive packages using CDM ignition.
Because Mercury used several ignition systems during this period, year and horsepower alone do not guarantee fitment. The most accurate method is to confirm the engine uses CDM ignition and compare the original wire to 84-813706A56, 84-821945A61 or 857124A1.
SportJet & Performance Applications
The same CDM architecture was used on a number of Mercury SportJet and performance two-stroke packages, making these wires useful in applications where heat and vibration can be more severe than normal recreational service.
SportJet engines, high-performance outboards, and boats that spend extended time at elevated RPM benefit from keeping every part of the ignition system in good condition.
A cracked or internally damaged plug wire can produce symptoms that look like a failing CDM, stator, or trigger, making proper inspection important before replacing more expensive ignition components.
When to Replace CDM Spark Plug Wires
Old ignition leads should be inspected whenever spark plugs or CDMs are serviced. Pay particular attention to cracked insulation, burned areas, loose terminals, green corrosion inside the boots, damaged connectors, or evidence of arcing.
A wire can also fail internally without obvious exterior damage. If an engine develops an intermittent cylinder drop that changes with heat or vibration, the high-tension lead should be included in the diagnostic process.
For older engines still running original wires, replacing all cylinders at the same time can provide a consistent ignition baseline.
Buckshot Racing #77 Installation Tech Tip
Route the replacement wire the same way as the original, keeping it clear of the flywheel, throttle linkage, sharp edges, and hot exhaust surfaces. Make sure both terminal ends fully engage before sliding the black boots into position.
Do not pull the wire tight between the CDM and spark plug. Leave enough length for engine vibration and normal movement without allowing excess cable to rub against surrounding components.
If the engine still has an ignition problem after replacing the wire, continue diagnosing the spark plug, CDM module, trigger, stator, grounds, stop circuit, and associated wiring rather than assuming the new lead will fix every no-spark condition.
The Buckshot Racing #77 High-Performance Blue 8mm CDM Spark Plug Wire provides a clean, durable replacement for compatible Mercury, Mariner, Force, and SportJet engines using 84-813706A56, 84-821945A61, or 857124A1 high-tension leads from the 1993-2010 CDM ignition era.
Contact Mike Hill at +1-714-697-1716 for tech support.