The Fat Boy Jet Kit is our exclusive solution for fine-tuning Mercury 2.0 and 2.4-liter WH carburetors and 2.0 and 2.5-Liter WMV series carburetors running on a cross-drill reed plate, which requires about 10 jets over non-cross drilled.
 
Designed to help you dial in reliability and peak performance, these jets replace Mercury OEM jets with high-quality, precision-machined components that ensure your 2-stroke outboard runs efficiently under demanding conditions.
 
Each jet is laser-marked for easy identification, providing the clarity and quality you need for high-performance and recreational outboards.
 
The Fat Boy Jet Kit includes a total of fourteen (14) jets designed to match the fuel demand of Mercury WH and WMV carburetors on cross-drilled race motors:
 
2 x 88 Jet Size 0.088" > Replaces OEM Part # 1395-6202
2 x 90 Jet Size 0.090" > Replaces OEM Part # 1395-6247
2 x 92 Jet Size 0.092" > Replaces OEM Part # 1395-5733
2 x 94 Jet Size 0.094" > Replaces OEM Part # 1395-8423
2 x 96 Jet Size 0.096" > Replaces OEM Part # 1399-6249
2 x 98 Jet Size 0.098" > Replaces OEM Part # 1395-7335
2 x 100 Jet Size 1.000" > Break-In Jets
 
This comprehensive set replaces Mercury OEM jets, providing reliable performance for a wide-range of applications.
 
Best Practices for Jetting a Mercury 2-Stroke Outboard
 
Getting the jetting right on your 2-stroke Mercury outboard is essential for achieving optimal power and efficiency. Follow these best practices to ensure your engine performs at its best:
 
Choose the Right Jet Size
Select a jet size appropriate for your engine’s displacement, carburetor type, and environmental conditions. Use smaller jets at higher altitudes or in cooler weather, and larger jets for sea-level or high-performance setups.
 
Monitor Engine Performance
Pay attention to symptoms of improper jetting, such as overheating, hesitation, or excessive smoke. A lean mixture (jet too small) can cause engine damage, while a rich mixture (jet too large) may lead to fouling and inefficiency.
 
Test and Adjust Gradually
Make incremental changes and test your engine under load after each adjustment. Check for smooth throttle response, strong acceleration, and clean top-end performance. Step jettings allows you to make incremental changes typically fatter jets on the bottom carbs to deal with the higher temparatures. ie top carbs 94s, middle 96s, bottom 98s.
 
Maintain Your Carburetors
Regularly clean and inspect your carburetors to ensure debris doesn’t restrict fuel flow. Replace worn or clogged jets with precision components like those in the Fat Boy Kit.
 
The Fat Boy Jet Kit provides a durable, high-quality solution for optimizing your Mercury 2-stroke outboard’s carburetor jetting.
 
Designed specifically for the main jets found in WH and WMV carburetors, this kit helps you achieve the performance and reliability you need for recreational and high-performance boating.
 
Includes ten (14) main jets: 2 x 88s, 2 x 90s, 2 x 92s, 2 x 94s, 2 x 96s, 2 x 98s, 2 x 100s. 
 
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