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Start ShoppingMIKUNI F4/042-240 Hex Main Jets - Precision Fuel Control for High-Performance Engines
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Description
Elevate your engine's performance with MIKUNI's F4/042-240 Hex Main Jets, engineered to deliver precise fuel-air mixture control for maximum power and efficiency. These high-quality jets are essential for optimizing fuel delivery in carbureted engines, ensuring smooth operation across a wide range of RPMs and load conditions.
Key Features
- Hexagonal Jet Design: Ensures secure, leak-free installation and easy adjustment for fine-tuning fuel flow.
- Durable Brass Construction: Resists corrosion and maintains precision even in demanding environments.
- Universal Compatibility: Fits most MIKUNI carburetor models for a wide range of powersports applications.
- High-Flow Performance: Optimized for high-output engines requiring precise fuel metering.
- Easy Installation: Streamlined design reduces setup time and minimizes maintenance hassle.
Why Choose This Product
Whether you're tuning a racing engine or enhancing daily-use performance, these jets offer unmatched reliability and precision. Their robust construction ensures long-term durability, while the hexagonal design simplifies adjustments for perfect fuel-air balance. Ideal for riders seeking to maximize power, improve throttle response, and achieve consistent performance in all riding conditions.
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Elevate your engine's performance with MIKUNI's F4/042-240 Hex Main Jets, engineered to deliver precise fuel-air mixture control for maximum power and efficiency. These high-quality jets are essential for optimizing fuel delivery in carbureted engines, ensuring smooth operation across a wide range of RPMs and load conditions.
Key Features
- Hexagonal Jet Design: Ensures secure, leak-free installation and easy adjustment for fine-tuning fuel flow.
- Durable Brass Construction: Resists corrosion and maintains precision even in demanding environments.
- Universal Compatibility: Fits most MIKUNI carburetor models for a wide range of powersports applications.
- High-Flow Performance: Optimized for high-output engines requiring precise fuel metering.
- Easy Installation: Streamlined design reduces setup time and minimizes maintenance hassle.
Why Choose This Product
Whether you're tuning a racing engine or enhancing daily-use performance, these jets offer unmatched reliability and precision. Their robust construction ensures long-term durability, while the hexagonal design simplifies adjustments for perfect fuel-air balance. Ideal for riders seeking to maximize power, improve throttle response, and achieve consistent performance in all riding conditions.
| SKU | GM8BAB4E51 |
|---|---|
| MPN | F4/042-240 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various Japanese | VM, BS, HSR, TM series carburetors | 1980-2025 |
| Honda | CRF250R, CRF450R, XR series | 1990-2025 |
| Yamaha | YZ/WR 250/450, TTR series | 1985-2025 |
| Kawasaki | KX250/450, KLX series | 1980-2025 |
Frequently Asked Questions
Main jet size depends on your elevation, temperature, exhaust, air filter, and riding style. Start with factory recommendation and adjust based on plug reads.
No, this is specifically for Mikuni carburetors. Keihin uses different threading.
Single jets are perfect for fine-tuning after initial rejetting. Full kits good for complete rebuilds.
F4/042 series fits most VM and BS series round slide Mikuni carbs. Check your carb model number.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Small flathead screwdriver
- Jet needle holder tool (optional)
Pro Tips
- Clean all carb passages thoroughly
- Verify float height after rejetting
- Install main jets dry - no carb cleaner residue
Common Mistakes to Avoid
- Not cleaning carb passages before installing new jet
- Incorrect jet sizing for your setup
Comparison vs Stock/OEM
Direct OEM replacement or performance upgrade
Improvements
- Precision machined brass construction
- Consistent fuel metering
- Ideal for elevation/temp changes
Considerations
- Must match your specific carb model
Durability & Warranty
Expected Lifespan
Lifetime (does not wear out)
Warranty
Limited manufacturer warranty
Maintenance
Inspect for debris during carb cleaning
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