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Start ShoppingMIKUNI F4/042-370 Hex Main Jet - Precision Carburetor Tuning Jet for High-Performance Engines
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Description
Elevate your engine's performance with the MIKUNI F4/042-370 Hex Main Jet, engineered for precise fuel metering and reliable operation in high-performance carburetor systems. This essential tuning component ensures optimal air-fuel ratios for power, efficiency, and smooth throttle response.
Key Features
- Hex (6-Sided) Design: Provides unmatched security during installation, preventing accidental loosening under high-speed or high-vibration conditions.
- Brass/Alloy Construction: Durable, corrosion-resistant material ensures long-lasting performance and accurate fuel flow control.
- Standard Mikuni Thread: Compatible with all Mikuni carburetor models for seamless integration and easy replacement.
- 370cc Jet Size: Optimized for mid-range power delivery, ideal for street bikes, off-road vehicles, and racing applications.
Why Choose This Product
Whether you're fine-tuning a sport bike or upgrading an off-road rig, the F4/042-370 delivers unmatched precision. Its hex configuration eliminates the risk of cross-threading, while the premium material ensures consistent fuel flow under extreme conditions. This jet is a must-have for riders seeking to maximize engine performance without compromising reliability.
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Elevate your engine's performance with the MIKUNI F4/042-370 Hex Main Jet, engineered for precise fuel metering and reliable operation in high-performance carburetor systems. This essential tuning component ensures optimal air-fuel ratios for power, efficiency, and smooth throttle response.
Key Features
- Hex (6-Sided) Design: Provides unmatched security during installation, preventing accidental loosening under high-speed or high-vibration conditions.
- Brass/Alloy Construction: Durable, corrosion-resistant material ensures long-lasting performance and accurate fuel flow control.
- Standard Mikuni Thread: Compatible with all Mikuni carburetor models for seamless integration and easy replacement.
- 370cc Jet Size: Optimized for mid-range power delivery, ideal for street bikes, off-road vehicles, and racing applications.
Why Choose This Product
Whether you're fine-tuning a sport bike or upgrading an off-road rig, the F4/042-370 delivers unmatched precision. Its hex configuration eliminates the risk of cross-threading, while the premium material ensures consistent fuel flow under extreme conditions. This jet is a must-have for riders seeking to maximize engine performance without compromising reliability.
| SKU | GM86A1CB54 |
|---|---|
| MPN | F4/042-370 |
| Brand | MIKUNI |
| Category | Jets |
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Frequently Asked Questions
The number indicates the jet size/orifice diameter. Larger numbers = richer fuel mixture. The 370 is a mid-range main jet size commonly used for street and trail applications.
Signs you need rejetting: poor fuel economy, hesitation on acceleration, black sooty spark plugs (too rich), or white/fouled plugs (too lean). A 370 is suitable for stock or mildly modified engines.
Hex jets have 6 flat sides for wrench grip, making them easier to install/remove without slipping. Round jets require a specialized jet tool. Hex design is more user-friendly for home mechanics.
No - verify your carburetor model first. The F4/042 designation indicates compatibility with specific Mikuni carburetors. Check your carb's part number before ordering.
Individual jets are available. Many tuners buy multiple sizes (360, 370, 380) to dial in the perfect mixture for their specific engine and riding conditions.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Hex wrench or socket (typically 5mm or 6mm depending on jet size)
- Carburetor removal tools (if full carburetor service)
- Clean workspace
Pro Tips
- Keep jets organized by size - they look similar but perform very differently
- Clean the jet bore with carburetor cleaner before installation
- Use gentle pressure when seating the jet - it should seat smoothly
- Document your current jetting before making changes for reference
- Test ride after jetting changes to verify performance improvement
Common Mistakes to Avoid
- Over-tightening the jet, which can strip the brass threads
- Installing incorrect jet size for your tuning needs
- Not cleaning the jet bore before installation
- Failing to verify correct jet size before ordering
Comparison vs Stock/OEM
Improvements
- Ability to optimize for specific riding conditions
- Better performance at altitude
- Improved throttle response when properly sized
- Cost-effective tuning solution
Considerations
- Requires knowledge of carburetor tuning
- Incorrect sizing can worsen performance
- May need multiple jets to find optimal size
- Works best with other jetting components (needle, clip)
Durability & Warranty
Expected Lifespan
Indefinite if properly maintained - brass jets don't wear out
Warranty
Typically not warranted as tuning component
Maintenance
No maintenance required - inspect for debris before reinstallation
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