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Start ShoppingMIKUNI F4/042-75 Hex Main Jets - High-Performance Fuel Jet Kit for Powersports Engines
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Description
Upgrade your powersports engine's fuel delivery system with MIKUNI's F4/042-75 Hex Main Jets. These precision-machined fuel jets ensure accurate air-fuel mixture ratios for enhanced power, efficiency, and engine longevity.
Key Features
- Hexagonal Main Jet Design: Ensures precise fuel metering for consistent performance across varying engine loads.
- Stainless Steel Construction: Resists corrosion and maintains accuracy in harsh environments.
- Direct Replacement Compatibility: Fits MIKUNI F4 carburetors for seamless installation.
- High-Flow Performance: Optimizes fuel delivery for increased horsepower and throttle response.
Why Choose This Product
Whether you're tuning a dirt bike, ATV, or off-road motorcycle, these main jets deliver reliable fuel flow for peak engine performance. The durable stainless steel construction ensures long-term accuracy, while the hexagonal design provides superior fuel atomization. Perfect for riders seeking precise control over their engine's air-fuel mixture without compromising durability or performance.
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Upgrade your powersports engine's fuel delivery system with MIKUNI's F4/042-75 Hex Main Jets. These precision-machined fuel jets ensure accurate air-fuel mixture ratios for enhanced power, efficiency, and engine longevity.
Key Features
- Hexagonal Main Jet Design: Ensures precise fuel metering for consistent performance across varying engine loads.
- Stainless Steel Construction: Resists corrosion and maintains accuracy in harsh environments.
- Direct Replacement Compatibility: Fits MIKUNI F4 carburetors for seamless installation.
- High-Flow Performance: Optimizes fuel delivery for increased horsepower and throttle response.
Why Choose This Product
Whether you're tuning a dirt bike, ATV, or off-road motorcycle, these main jets deliver reliable fuel flow for peak engine performance. The durable stainless steel construction ensures long-term accuracy, while the hexagonal design provides superior fuel atomization. Perfect for riders seeking precise control over their engine's air-fuel mixture without compromising durability or performance.
| SKU | GMEC02FAF3 |
|---|---|
| MPN | F4/042-75 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various (Mikuni VM/PF/BS series carbs) | VM26-428, VM34-460, BS34-22, HSR42, TM40 | 1985-2024 |
| Yamaha | YFM350X Warrior, YFM400 Big Bear | 1990-2005 |
| Honda | TRX300 FourTrax | 1987-1999 |
| Suzuki | LT250R Quadracer, LT80 | 2000-2014 |
Frequently Asked Questions
Fits Mikuni VM, PF, BS, HSR, and TM series carbs with main jet port. Confirm your carb model.
Use plug chop method or wideband O2 sensor to measure air/fuel ratio. 042 is mid-range for stock to mildly modified setups.
Hex head style (F4 series) for easier installation/removal without special tools.
Yes, if equipped with compatible Mikuni carb. Check fitment tab for your model.
F4 is hex style for VM carbs; BS30/34 are round for round-port carbs.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Small flathead screwdriver
- Needle nose pliers
Pro Tips
- Mark jet size before removal. Clean threads. Test run after install to check fuel mixture.
Common Mistakes to Avoid
- Installing without removing old jet fully
- Not cleaning carb bowl before install
Comparison vs Stock/OEM
Direct OEM replacement or upgrade from stock jets
Improvements
- Precise fuel metering for better performance
- Easier hex head for tuning
- Consistent brass quality
Considerations
- Requires rejetting for mods like exhaust/intake/altitude changes
Durability & Warranty
Expected Lifespan
Indefinite with proper use (replace if damaged/clogged)
Warranty
Limited lifetime (manufacturer defect only)
Maintenance
Inspect during carb cleaning; clean with carb cleaner, avoid abrasives
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