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Start ShoppingMikuni FN100604-125 Large Round Main Jet - High-Performance Carburetor Fuel Control
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Description
Upgrade your Mikuni carburetor's fuel delivery system with this precision-engineered Large Round Main Jet. Designed for 125cc engines, this brass jet ensures consistent fuel flow across throttle ranges, delivering reliable power and responsiveness for riders who demand performance.
Key Features
- Part Number FN100604-125: Direct replacement for original equipment Mikuni jets, ensuring perfect fit and function.
- Brass Construction: Durable, corrosion-resistant material withstands high temperatures and fuel exposure for long-lasting performance.
- 125cc Jet Size: Optimized fuel flow for mid-to-high throttle positions, balancing power and efficiency.
- Large Round Shape: Standard design for easy installation and precise fuel metering in carburetor systems.
- Carburetor Compatibility: Works with Mikuni carburetors for 2-stroke and 4-stroke engines, including popular models like the TMX and TZR.
Why Choose This Product
Upgrade to this Mikuni main jet for smoother throttle response, improved fuel efficiency, and enhanced engine performance. The brass material resists wear and ensures accurate fuel delivery, while the 125cc size provides the perfect balance between power and control. Ideal for riders seeking reliable, high-performance fuel delivery without compromising on durability or compatibility.
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Upgrade your Mikuni carburetor's fuel delivery system with this precision-engineered Large Round Main Jet. Designed for 125cc engines, this brass jet ensures consistent fuel flow across throttle ranges, delivering reliable power and responsiveness for riders who demand performance.
Key Features
- Part Number FN100604-125: Direct replacement for original equipment Mikuni jets, ensuring perfect fit and function.
- Brass Construction: Durable, corrosion-resistant material withstands high temperatures and fuel exposure for long-lasting performance.
- 125cc Jet Size: Optimized fuel flow for mid-to-high throttle positions, balancing power and efficiency.
- Large Round Shape: Standard design for easy installation and precise fuel metering in carburetor systems.
- Carburetor Compatibility: Works with Mikuni carburetors for 2-stroke and 4-stroke engines, including popular models like the TMX and TZR.
Why Choose This Product
Upgrade to this Mikuni main jet for smoother throttle response, improved fuel efficiency, and enhanced engine performance. The brass material resists wear and ensures accurate fuel delivery, while the 125cc size provides the perfect balance between power and control. Ideal for riders seeking reliable, high-performance fuel delivery without compromising on durability or compatibility.| SKU | GME3585C77 |
|---|---|
| MPN | FN100604-125 |
| Brand | MIKUNI |
| Category | Jets |
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Featured Review
| Make | Model | Years |
|---|---|---|
| Various Japanese | Carbureted motorcycles/ATVs (Keihin/Mikuni carbs) | 1980-2025 |
| Honda | XR series, CRF250R, CRF450R (pre-fuel injection) | 1990-2010 |
| Yamaha | PW series, YZ, WR (2-stroke/4-stroke carbureted) | 1985-2020 |
| Suzuki | RM, DR-Z, LT series ATVs | 1980-2015 |
| Kawasaki | KX, KLX (carbureted models) | 1990-2020 |
Frequently Asked Questions
The main jet controls fuel flow through the main fuel circuit, which operates at mid-to-high throttle positions. It affects engine performance, fuel economy, and throttle response in that range.
Jet size depends on your engine's displacement, altitude, air temperature, and modifications. Start with the manufacturer's recommended size and adjust based on plug color and performance. Higher numbers = richer mixture.
The 125 size is common for small-displacement engines (50cc-250cc range). Verify your carburetor model and engine specifications before purchasing.
Yes, main jet replacement is a beginner-friendly task. You'll need basic tools and about 15 minutes. Carburetor removal may be more involved depending on your bike.
Yes, modifications like air filter upgrades, exhaust changes, or engine tuning typically require rejetting to maintain proper fuel-air ratio and performance.
Installation Guide
Difficulty
Easy
Est. Time
15 min
Tools Required
- Screwdrivers (Phillips and flat-head)
- Small wrench or socket set
- Carburetor cleaning tools (optional)
- Gasket scraper
Pro Tips
- Clean carburetor thoroughly while disassembled
- Use gasket sealant on bowl gasket during reassembly
- Hand-tighten jet gently - do not force
- Test idle and throttle response after installation
- Keep old jet for reference or backup
Common Mistakes to Avoid
- Over-tightening jet (can strip threads)
- Not cleaning carburetor before reassembly
- Forgetting to drain fuel before disassembly
- Installing jet upside down
Durability & Warranty
Expected Lifespan
Indefinite if properly maintained; replaced when tuning or if damaged
Warranty
Typically covered under manufacturer warranty if defective
Maintenance
No maintenance required; inspect for debris or damage during carburetor service
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