The Buckshot Racing #77 custom laser-marked main jet kit featuring jet sizes 70 through 78 is engineered for Mercury outboard owners and performance tuners looking to dial in their 2-stroke engine’s fuel system with precision.
This kit includes two (2) of each main jet size—designed as direct replacements for Mercury OEM part numbers—providing critical flexibility for fine-tuning a wide range of engine and environmental conditions. Each jet is laser-etched with its size to ensure permanent identification under all maintenance or tuning scenarios.
This kit includes the following jet sizes and their corresponding Mercury OEM part numbers:
Jet Size 0.070 Inch – Mercury OEM Part Number 1395-6030
Jet Size 0.072 Inch – Mercury OEM Part Number 1395-6207
Jet Size 0.074 Inch – Mercury OEM Part Number 1399-3794
Jet Size 0.076 Inch – Mercury OEM Part Number 1399-3796
Jet Size 0.078 Inch – Mercury OEM Part Number 1395-6680
These main jets are fully compatible with Mercury WH, WMH, and WMV carburetors, making them ideal for a variety of Mercury 2-stroke outboard engines including 2.0L, 2.4L, 2.5L, and 3.0L outboards.
This includes performance and recreational models such as the Mercury 135 HP, 150 HP, 175 HP, 200 HP, 225 HP, and 245 HP engines, as well as high-performance variants like the XR2, XR4, XR6, SST-120, SST-140, and vintage Black Max outboards.
Main jets are vital for regulating the fuel entering the combustion chamber through the carburetor.
In the WH, WMH, and WMV series carburetors, these jets control the main fuel circuit, critical to mid- and high-RPM power delivery. Accurate jet sizing ensures optimal combustion characteristics, especially important when tuning for power, reliability, or fuel efficiency.
This kit provides a crucial range of smaller jet sizes—ideal for leaner tuning profiles often required at lower altitudes, in cooler weather, or when optimizing for better fuel efficiency without sacrificing combustion stability.
Choosing the correct jet size helps achieve:
Optimal Power Delivery – Ensuring the air-fuel ratio is correct across all throttle positions.
Engine Protection – Avoiding lean conditions that can cause overheating or detonation.
Tuning Versatility – Enabling precise fuel mapping after modifications such as intake changes, port work, or custom exhaust.
Fuel Efficiency – Reducing unnecessary fuel consumption while maintaining strong performance.
All jets in this kit are marked with precision laser etching for identification during tuning or maintenance.
Each jet directly replaces OEM parts 1395-6030, 1395-6207, 1399-3794, 1399-3796, and 1395-6680, ensuring seamless compatibility with factory Mercury outboard carburetor specifications.
Whether you're performing altitude compensation, making seasonal adjustments, or refining your powerband after engine modifications, the Buckshot Racing #77 jet kit for WH, WMH, and WMV carburetors delivers accurate and reliable options to achieve the performance and reliability Mercury 2-stroke outboards are known for.
Include ten (10) main jets: 2 x 70s, 2 x72s, 2 x 74s, 2 x 76s, 2 x 78s.
Tuning Notes:
In high-performance applications, it is possible to stagger main jet sizes across the carburetors to account for how heat distributes throughout the engine—especially during extended wide-open throttle (WOT) operation.
As the engine runs at full power, the lower cylinders (typically cylinders 5 and 6) tend to build heat by the exhaust exit and run hotter compared to the middle ones (3 and 4) and the top cylinders (1 and 2). This heat buildup can lead to a leaner air-fuel mixture in lower cylinders if the jets are all the same size.
To compensate for this, slightly larger main jets are installed in the bottom two carburetors that feed cylinders 5 and 6, and also 3 and 4.
This enriches the fuel mixture for those cylinders, helping to keep temperatures under control and prevent potential engine damage like detonation or piston scuffing. The middle and upper carburetors use slightly smaller jets, tuned to match their thermal and airflow characteristics.
This technique ensures a more balanced fuel delivery across all cylinders, which can improve reliability and overall engine performance under high-load conditions.
For more information, contact Mike Hill at 714-697-1716 or email mike@buckshotracing77.com