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Start ShoppingMIKUNI F4/042-270 Hex Main Jets - High-Performance Brass Carburetor Jets for Powersports
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Description
Upgrade your powersports engine's performance with these MIKUNI F4/042-270 Hex Main Jets. Engineered for precision fuel delivery, these brass jets ensure reliable combustion efficiency and smooth throttle response in motorcycles, ATVs, and off-road vehicles.
Key Features
- Brass Construction: Durable, corrosion-resistant material withstands high temperatures and fuel exposure for long-lasting performance.
- Hex Head Design: Easy-to-adjust hex threading simplifies maintenance and tuning for precise air-fuel ratio control.
- M5 x 0.75 Thread: Universal compatibility with standard carburetor systems ensures seamless installation.
- #270 Size: Optimized flow rate for high-performance engines requiring precise fuel metering.
Why Choose This Product
These MIKUNI jets deliver consistent power delivery and improved fuel efficiency by maintaining optimal combustion. The brass material resists clogging and wear, while the hex head design enables quick adjustments during tuning. Perfect for riders seeking reliable performance in demanding off-road and street environments.
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Upgrade your powersports engine's performance with these MIKUNI F4/042-270 Hex Main Jets. Engineered for precision fuel delivery, these brass jets ensure reliable combustion efficiency and smooth throttle response in motorcycles, ATVs, and off-road vehicles.
Key Features
- Brass Construction: Durable, corrosion-resistant material withstands high temperatures and fuel exposure for long-lasting performance.
- Hex Head Design: Easy-to-adjust hex threading simplifies maintenance and tuning for precise air-fuel ratio control.
- M5 x 0.75 Thread: Universal compatibility with standard carburetor systems ensures seamless installation.
- #270 Size: Optimized flow rate for high-performance engines requiring precise fuel metering.
Why Choose This Product
These MIKUNI jets deliver consistent power delivery and improved fuel efficiency by maintaining optimal combustion. The brass material resists clogging and wear, while the hex head design enables quick adjustments during tuning. Perfect for riders seeking reliable performance in demanding off-road and street environments.
| SKU | GM6D6F72DD |
|---|---|
| MPN | F4/042-270 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various Japanese | Carbureted motorcycles/ATVs | 1985-2024 |
| Yamaha | XT600, YZ250F | 1990-2005 |
| Suzuki | DR350, RM250 | 1987-2000 |
| Kawasaki | KX250, KLX300 | 1985-2010 |
| Honda | XR250R, CRF450R (pre-PGM-FI) | 1982-2007 |
Frequently Asked Questions
Fits most Mikuni round-slide carbs (VM26-VM34, BS32-38, TM/HCR series). Confirm bore size and model.
Larger number = richer mixture. Start with stock size and adjust based on plug reads, EGT, or altitude/temp changes.
Yes, main jet controls fuel from 1/2 to full throttle. Pair with pilot jet for full tuning.
No, this is for carbureted engines only.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Flathead screwdriver
- Needle nose pliers
Pro Tips
- Mark current jet size before removal. Use carb cleaner on o-ring. Test in small increments (2-4 sizes) for tuning
Common Mistakes to Avoid
- Installing wrong jet size
- Not cleaning carb passages before install
Comparison vs Stock/OEM
Direct replacement for OEM Mikuni jets; precision machined brass same as factory
Improvements
- Consistent flow metering
- Easier hex installation
- Available in sizes OEM may not offer
Considerations
- Aftermarket identical to OEM quality
Durability & Warranty
Expected Lifespan
Engine life (5+ years); fuel corrosion resistant
Warranty
Lifetime manufacturer defect warranty (Mikuni)
Maintenance
Inspect during carb cleaning; replace if deformed
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