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Start ShoppingMIKUNI F4/042-70 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 F4/042-70 Hex Main Jets. These precision-engineered components ensure optimal fuel-air mixture for enhanced power, responsiveness, and consistent performance across a wide range of powersports engines.
Key Features
- Hexagonal Jet Design: Ensures secure, leak-free installation and precise fuel flow control.
- Durable Brass Construction: Resists corrosion and maintains accuracy under extreme operating conditions.
- Universal Compatibility: Fits most MIKUNI carburetor models for easy integration into existing systems.
- High-Flow Performance: Optimizes fuel delivery for improved throttle response and engine efficiency.
Why Choose This Product
MIKUNI jets deliver unmatched reliability and performance for riders demanding precision. The hexagonal design simplifies adjustment while maintaining a secure fit, reducing the risk of fuel leaks. Crafted from high-grade brass, these jets withstand harsh environments while maintaining consistent fuel flow. Whether you're tuning a motorcycle, ATV, or off-road vehicle, these jets provide the accuracy needed to unlock your engine's full potential.
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Upgrade your engine's fuel delivery system with MIKUNI's F4/042-70 Hex Main Jets. These precision-engineered components ensure optimal fuel-air mixture for enhanced power, responsiveness, and consistent performance across a wide range of powersports engines.
Key Features
- Hexagonal Jet Design: Ensures secure, leak-free installation and precise fuel flow control.
- Durable Brass Construction: Resists corrosion and maintains accuracy under extreme operating conditions.
- Universal Compatibility: Fits most MIKUNI carburetor models for easy integration into existing systems.
- High-Flow Performance: Optimizes fuel delivery for improved throttle response and engine efficiency.
Why Choose This Product
MIKUNI jets deliver unmatched reliability and performance for riders demanding precision. The hexagonal design simplifies adjustment while maintaining a secure fit, reducing the risk of fuel leaks. Crafted from high-grade brass, these jets withstand harsh environments while maintaining consistent fuel flow. Whether you're tuning a motorcycle, ATV, or off-road vehicle, these jets provide the accuracy needed to unlock your engine's full potential.
| SKU | GM85C2826B |
|---|---|
| MPN | F4/042-70 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various (Mikuni VM/PF/BS carbureted bikes) | VM26/VM34/VM36/VM38/BS34/BS36/BS38/BS40 carbs | 1985-2024 |
| Honda | XR250R, XR400R, XR600R, XR650L | 1990-2005 |
| Yamaha | XT350, TT350, YZ250, WR250 | 1986-2002 |
| Suzuki | DR350, DRZ400 | 1993-2020 |
Frequently Asked Questions
Fits most Mikuni round-slide carbs like VM26-VM40, BS30-BS40 series used on dirt bikes, dual sports, and vintage models.
Yes, OEM-style hex main jet for precise fuel metering adjustments.
Check your current main jet (stamped on side) or use a jet kit calculator based on mods, altitude, and temp.
#170 size suits 250-500cc bikes; larger engines may need #180+.
Hex jets are easier to remove/install without special tools; same flow rates.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Small flathead screwdriver
- 12-point socket (7mm or 8mm)
- Jet cleaning wire or carb cleaner
Pro Tips
- Remove carb float bowl first. Note original jet size. Clean all passages. Use thread lube if reusing old jets.
Common Mistakes to Avoid
- Not cleaning jet seat before install
- Installing wrong size jet
- Over-tightening which strips threads
Comparison vs Stock/OEM
Direct OEM equivalent from Mikuni (OEM for many Japanese bikes)
Improvements
- Precision machined for consistent flow
- Easier hex head for tuning
- Corrosion-resistant brass
Considerations
- None - identical to factory spec
Durability & Warranty
Expected Lifespan
Indefinite with proper cleaning (carb service every 20-50 hours)
Warranty
Limited lifetime from Mikuni against defects
Maintenance
Remove and clean/ultrasonic during carb rebuilds; inspect for wear/clogging
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