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Start ShoppingMIKUNI F4/042-120 Hex Main Jets - High-Performance Brass Fuel Jets for Racing & Off-Road
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Description
Upgrade your engine's fuel delivery system with MIKUNI's F4/042-120 Hex Main Jets. These precision-engineered brass jets deliver consistent fuel flow for enhanced power, responsiveness, and reliability in demanding off-road and racing environments.
Key Features
- Brass Construction: Durable, corrosion-resistant material ensures long-lasting performance in harsh conditions.
- #120 Jet Size: Precisely calibrated for optimal fuel metering in high-output engines.
- Hex Head Thread: Simplifies installation and adjustment with a secure, tamper-resistant fit.
- 1/4-32 Thread: Universal compatibility with most carburetor setups for easy integration.
- 0.5in Length: Compact design reduces weight while maintaining structural integrity.
Why Choose This Product
MIKUNI's Hex Main Jets combine racing-proven engineering with user-friendly design. The brass material resists clogging and maintains flow accuracy under extreme temperatures, while the hex thread ensures a leak-proof connection. Whether you're tuning a competition motorcycle or optimizing your off-road rig, these jets deliver consistent performance without compromising durability.
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Upgrade your engine's fuel delivery system with MIKUNI's F4/042-120 Hex Main Jets. These precision-engineered brass jets deliver consistent fuel flow for enhanced power, responsiveness, and reliability in demanding off-road and racing environments.
Key Features
- Brass Construction: Durable, corrosion-resistant material ensures long-lasting performance in harsh conditions.
- #120 Jet Size: Precisely calibrated for optimal fuel metering in high-output engines.
- Hex Head Thread: Simplifies installation and adjustment with a secure, tamper-resistant fit.
- 1/4-32 Thread: Universal compatibility with most carburetor setups for easy integration.
- 0.5in Length: Compact design reduces weight while maintaining structural integrity.
Why Choose This Product
MIKUNI's Hex Main Jets combine racing-proven engineering with user-friendly design. The brass material resists clogging and maintains flow accuracy under extreme temperatures, while the hex thread ensures a leak-proof connection. Whether you're tuning a competition motorcycle or optimizing your off-road rig, these jets deliver consistent performance without compromising durability.
| SKU | GM5C1F4C22 |
|---|---|
| MPN | F4/042-120 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various | Carbureted motorcycles/ATVs | 1980-2025 |
Frequently Asked Questions
Fits most Mikuni VM series round-slide carbs (VM26-VM44), HSR42/45, BS series; not for TM flatslide.
Use plug chop method or wideband O2 sensor; #120 is common for mid-range tuning on 250-500cc engines.
Hex jets are for easier installation/removal; same flow as round/square equivalents.
No, Mikuni jets have different threading; use Keihin PDS/PWK jets for those.
Installation Guide
Difficulty
Easy
Est. Time
5 min
Tools Required
- Small flathead screwdriver
- Jet wrench or needle nose pliers
Pro Tips
- Remove carb bowl first, note float height, use carb cleaner on old jets
Common Mistakes to Avoid
- Dropping jet into carb body
- Not cleaning carb before install
Comparison vs Stock/OEM
Direct replacement for OEM Mikuni jets; precision machined brass
Improvements
- Consistent flow rates
- Easier hex head for tuning
- Corrosion resistant
Considerations
- None - identical to factory spec
Durability & Warranty
Expected Lifespan
Indefinite with proper cleaning
Warranty
Lifetime manufacturer defect warranty
Maintenance
Clean with carb cleaner every 10-20 hours; inspect for clogging
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