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Start ShoppingMIKUNI F4/042-50 Hex Main Jets - Precision Carburetor Jet for Optimal Fuel Delivery
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Description
Upgrade your carburetor's fuel delivery system with MIKUNI's precision-engineered F4/042-50 Hex Main Jets. These critical components ensure optimal air-fuel ratios for enhanced power, efficiency, and engine longevity across a range of powersports applications.
Key Features
- Hexagonal Design: Ensures precise fuel flow control and easy installation with standard tools
- Corrosion-Resistant Alloy: Durable construction withstands harsh operating conditions and fuel contaminants
- Exact Fitment: Specifically engineered for MIKUNI carburetor systems with 042-50 main jet ports
- Performance Optimization: Fine-tunes fuel metering for responsive throttle response and consistent power delivery
Why Choose This Product
MIKUNI main jets deliver unmatched reliability and performance for riders demanding precision fuel delivery. The hexagonal design simplifies maintenance while maintaining strict tolerances for accurate fuel metering. This essential component ensures your engine runs smoothly under various conditions, from daily commuting to off-road adventures. Whether you're tuning a motorcycle, ATV, or UTV, these jets provide the foundation for optimal engine performance and fuel efficiency.
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Upgrade your carburetor's fuel delivery system with MIKUNI's precision-engineered F4/042-50 Hex Main Jets. These critical components ensure optimal air-fuel ratios for enhanced power, efficiency, and engine longevity across a range of powersports applications.
Key Features
- Hexagonal Design: Ensures precise fuel flow control and easy installation with standard tools
- Corrosion-Resistant Alloy: Durable construction withstands harsh operating conditions and fuel contaminants
- Exact Fitment: Specifically engineered for MIKUNI carburetor systems with 042-50 main jet ports
- Performance Optimization: Fine-tunes fuel metering for responsive throttle response and consistent power delivery
Why Choose This Product
MIKUNI main jets deliver unmatched reliability and performance for riders demanding precision fuel delivery. The hexagonal design simplifies maintenance while maintaining strict tolerances for accurate fuel metering. This essential component ensures your engine runs smoothly under various conditions, from daily commuting to off-road adventures. Whether you're tuning a motorcycle, ATV, or UTV, these jets provide the foundation for optimal engine performance and fuel efficiency.
| SKU | GMBF138935 |
|---|---|
| MPN | F4/042-50 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various Yamaha | XT250, YZ250, WR250 | 1980-2025 |
| Various Honda | CRF250R, XR400R | 1990-2025 |
| Various Kawasaki | KX250, KLX300 | 1985-2025 |
| Various Suzuki | RM250, DR-Z400 | 1975-2025 |
Frequently Asked Questions
The '42' indicates the jet size/orifice diameter. Larger numbers = richer fuel mixture. Jet sizing affects fuel-to-air ratio in the carburetor.
Jet selection depends on altitude, temperature, engine modifications, and carburetor tuning. Check your carburetor manual or consult with a tuning specialist. Common sizes range from 30-50+.
No. Different Mikuni carburetors have different jet configurations. Verify your carburetor model (e.g., VM, TMX, TM, etc.) before purchasing.
Hex jets have a hexagonal head for easier removal/installation with a wrench. Round jets require a jet removal tool. Functionally, they perform the same.
Yes. Performance modifications (exhaust, intake, ignition) typically require rejetting to maintain proper fuel-air mixture and prevent running too lean or rich.
Installation Guide
Difficulty
Easy
Est. Time
15 min
Tools Required
- Carburetor removal tools (if replacing in-situ)
- Small hex wrench or jet removal tool
- Gasket scraper
- Clean rags
Pro Tips
- Gently seat the jet - do not force
- Clean carburetor thoroughly before reassembly
- Keep track of all small parts and gaskets
- Test run and adjust idle if needed after installation
- Document original jet size before replacement
Common Mistakes to Avoid
- Over-tightening the jet (can strip threads or crack brass)
- Not cleaning carburetor passages after removal
- Installing wrong jet size for application
- Not replacing gaskets when carburetor is opened
Durability & Warranty
Expected Lifespan
Indefinite if not damaged; brass jets are durable
Warranty
Typically covered under manufacturer warranty if defective
Maintenance
Clean periodically if carburetor is serviced; replace if damaged or clogged
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