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Start ShoppingMIKUNI F4/042-155 Hex Main Jets - Precision Fuel Delivery for High-Performance Engines
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Description
Upgrade your engine's fuel delivery system with MIKUNI's precision-engineered F4/042-155 Hex Main Jets. These critical components ensure optimal fuel-air mixture for enhanced power, efficiency, and reliable performance across a range of powersports applications.
Key Features
- Precision Engineering: Meticulously crafted for accurate fuel metering, ensuring peak engine performance under varying conditions.
- Durable Construction: Made from high-quality brass for long-lasting reliability and resistance to corrosion.
- Universal Compatibility: Designed to fit MIKUNI carburetor systems, simplifying installation and maintenance.
- Easy Installation: Streamlined design allows for quick replacement without compromising performance.
Why Choose This Product
Whether you're tuning a high-performance motorcycle, ATV, or off-road vehicle, these main jets deliver consistent fuel flow for smoother acceleration, better throttle response, and improved fuel efficiency. Their robust construction ensures they withstand harsh operating conditions, while the precise calibration helps maintain optimal engine performance. Ideal for riders seeking reliable, high-output power without compromising on durability or ease of use.
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Upgrade your engine's fuel delivery system with MIKUNI's precision-engineered F4/042-155 Hex Main Jets. These critical components ensure optimal fuel-air mixture for enhanced power, efficiency, and reliable performance across a range of powersports applications.
Key Features
- Precision Engineering: Meticulously crafted for accurate fuel metering, ensuring peak engine performance under varying conditions.
- Durable Construction: Made from high-quality brass for long-lasting reliability and resistance to corrosion.
- Universal Compatibility: Designed to fit MIKUNI carburetor systems, simplifying installation and maintenance.
- Easy Installation: Streamlined design allows for quick replacement without compromising performance.
Why Choose This Product
Whether you're tuning a high-performance motorcycle, ATV, or off-road vehicle, these main jets deliver consistent fuel flow for smoother acceleration, better throttle response, and improved fuel efficiency. Their robust construction ensures they withstand harsh operating conditions, while the precise calibration helps maintain optimal engine performance. Ideal for riders seeking reliable, high-output power without compromising on durability or ease of use.
| SKU | GMBFBDD217 |
|---|---|
| MPN | F4/042-155 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various Japanese | Carbureted motorcycles/ATVs | 1980-2025 |
| Yamaha | XT600, YZ250F, WR250 | 1990-2010 |
| Honda | XR series, CRF250R | 1985-2005 |
| Suzuki | DR-Z400, RM250 | 1995-2015 |
| Kawasaki | KX250, KLX300 | 1980-2020 |
Frequently Asked Questions
Fits most Mikuni round-slide carbs like VM26-VM34, TM40, HSR42/45, BS36/38/40.
Use a jetting kit or dyno tune; #155 is common for mid-range tuning at sea level or richer mixtures.
Yes, hex head (F4/042) for easier removal without special tools; same flow as round jets.
No, Mikuni jets have different threading; stick to brand-matched jets.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Small flathead screwdriver
- Jetting gauge or calipers
Pro Tips
- Remove carb, unscrew old jet with screwdriver, insert new one and snug gently. Always rejet in sets for balance.
Common Mistakes to Avoid
- Installing wrong size jet
- Not cleaning carb passages first
Comparison vs Stock/OEM
Direct replacement for OEM main jets; Mikuni is OEM on many Japanese bikes
Improvements
- Precision machining for consistent fuel flow
- Hex head for tool-free swaps
- Corrosion-resistant brass
Considerations
- Aftermarket tuning may require full carb sync
Durability & Warranty
Expected Lifespan
Indefinite with proper use; does not wear out
Warranty
Limited lifetime from Mikuni
Maintenance
Inspect for debris during carb cleans; replace if damaged
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