KEIHIN N424-21-50 Jet Nos

( Brand: Keihin ), ( Manufacturer Part Number: N424-21-50 ), ( Part Type: Jet )

Review KEIHIN #50 Jet Nos fits PILOT

The **Keihin N424-21-50 Pilot Jet** is a precision-engineered, high-performance fuel injection component designed specifically for carbureted engines, offering an optimal blend of reliability, efficiency, and adaptability for both stock and modified applications. Part of Keihin s renowned **N-Series** line, this **50-diameter pilot jet** is meticulously crafted to deliver consistent fuel metering under varying operating conditions, making it an ideal choice for enthusiasts seeking improved throttle response, smoother idle performance, and enhanced overall engine tuning. The **N424-21** designation indicates its compatibility with a wide range of carburetors, including popular models like the **Holley 4150, Edelbrock CA4, and Moroso 4150**, ensuring seamless integration with both stock and aftermarket setups. Constructed from high-grade **brass with a precision-machined orifice**, this jet is designed to resist clogging and corrosion, maintaining accurate fuel flow even under demanding conditions such as high-RPM driving, aggressive acceleration, or extended use in performance applications. Its **tapered internal design** minimizes fuel atomization issues, promoting a cleaner burn and reducing carbon buildup on intake valves a common concern in carbureted engines. Whether installed in a classic muscle car, a street rod, or a high-performance street machine, the **N424-21-50** provides a balanced fuel delivery solution that can be fine-tuned further through adjustments to the carburetor s idle mixture screws or by pairing it with complementary jets for optimal performance. Keihin s reputation for durability and precision ensures that this pilot jet will stand up to the rigors of daily driving while offering the flexibility to adapt to modifications such as performance camshafts, forced induction, or fuel system upgrades. For tuners and mechanics who demand consistency and performance, the **Keihin N424-21-50 Pilot Jet** is a dependable, high-quality component that bridges the gap between stock reliability and custom-tuned excellence.

### **Pros and Cons of Buying a Keihin N424-21-50 Pilot Jet (Nozzle Size 50)**

1. **High Performance and Efficiency** The N424 series is known for its precise fuel delivery and improved combustion, which can enhance engine performance, especially in high-compression or turbocharged applications. The pilot jet plays a crucial role in cold starts and idle stability, ensuring smoother operation.

2. **Durability and Reliability** Keihin is a well-regarded brand in the automotive and motorcycle fuel injection industry, known for producing high-quality components that withstand wear over time. The N424 carburetor is widely used in performance and stock applications, indicating its robustness.

3. **Compatibility with Modifications** If you re running a modified engine (e.g., increased compression, forced induction, or performance chips), the N424-21-50 pilot jet can be tuned to match the new power levels. It s often used in builds where precise fuel metering is critical.

4. **Aftermarket Support** Keihin components are widely available, and there is extensive tuning data, forums, and professional support for adjusting fuel delivery. This makes it easier to fine-tune the carburetor for optimal performance.

5. **Cold Start and Idle Stability** The pilot jet (50 in this case) is designed to provide a steady fuel flow during cold starts and idle, reducing stalling and rough running. A properly sized pilot jet ensures the engine doesn t flood or misfire under light loads.

6. **Cost-Effective for Performance Builds** Compared to full fuel injection systems, carburetors like the N424 are often more affordable to install and maintain. Upgrading individual jets (like the pilot jet) can be a budget-friendly way to improve performance without a full rebuild.

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1. **Learning Curve for Tuning** Carburetors require manual adjustment, and getting the pilot jet size (or other jets) correct can be tricky. Too small a pilot jet (like a 50 in some cases) may cause stalling or hesitation, while too large one can lead to flooding or poor high-RPM performance. Tuning experience is often necessary.

2. **Sensitivity to Fuel Quality** Carburetors are more sensitive to fuel impurities than fuel-injected engines. Poor-quality fuel can clog jets, leading to performance issues. Regular cleaning or maintenance is required to keep the carburetor running smoothly.

3. **Limited Flexibility for Extreme Mods** If you re running extreme power levels (e.g., 500 hp), a carburetor like the N424 may struggle to keep up without significant modifications (e.g., larger bodies, multiple jets, or auxiliary pumps). Fuel injection is often the better choice for high-power applications.

4. **Maintenance Requirements** Carburetors need regular cleaning, jet inspections, and occasional rebuilds. Neglecting maintenance can lead to poor performance, fuel waste, or even engine damage from rich mixtures.

5. **Potential for Flooding** If the pilot jet is oversized or the carburetor isn t tuned correctly, the engine may flood, especially during cold starts. This can cause cranking without ignition or rough idling until the excess fuel burns off.

6. **Less Precise Than Fuel Injection** While modern carburetors are advanced, they still can t match the precision of electronic fuel injection (EFI) in terms of real-time adjustments for different driving conditions. This can limit performance in dynamic situations.

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The **Keihin N424-21-50 pilot jet** is a solid choice for those looking to upgrade their carbureted engine s performance, particularly in applications where cold starts, idle stability, and moderate power gains are priorities. It offers durability, aftermarket support, and compatibility with various modifications. However, it requires tuning knowledge, regular maintenance, and isn t ideal for extreme power levels or situations where fuel injection would be more practical.

If you re running a stock or lightly modified engine and want a reliable, high-performance carburetor solution, the N424-21-50 pilot jet is a worthwhile investment **provided you re prepared to tune and maintain it properly**. For high-performance builds pushing 400 hp or more, fuel injection may ultimately be the better long-term solution.

- **Buy it if:** You re working with a carbureted engine, want improved cold starts/idle, and are willing to learn tuning. It s a great mid-range upgrade for performance builds.

- **Avoid it if:** You re running extreme power levels, lack carburetor tuning experience, or prefer the convenience of fuel injection.

- **Pair it with:** A reliable fuel system (clean fuel, proper fuel pressure), a carburetor tuning guide, and regular maintenance to maximize its lifespan and performance.

For best results, consult with a carburetor specialist or experienced tuner to ensure the pilot jet (and other jets) are correctly sized for your specific engine setup.

Details:

#50 Pilot Jet is new and in good condition, not original packaging. Items are shipped using USPS, UPS, and FedEx. Keihin N424-21-50 #50 Pilot Jet NOS.

If the original package is included it may show signs of wear. All parts are in stock and ready to ship.

part #: n4242150 prices

• $17.49-$29.07

specifications intakefuelmotorcycle:

• for models: Pilot
• brand: Keihin
• mpn: N424-21-50
• part type: Jet

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• credit card: Mastercard
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• city: Ashaway, Rhode Island
• rating: 99.9%
• # reviews: 135649

shipping intakefuelmotorcycle:

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• service: USPS Ground Advantage, USPS Priority Mail Flat Rate Envelope, UPS Next Day Air, UPS 2nd Day Air
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• type: Calculated

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general intakefuelmotorcycle:

• Motorcycle Scooter Parts Accessories > Air Intake Fuel Delivery > Other Air Intake Fuel Delivery
• condition: New other see details

offer intakefuelmotorcycle:

• best offers: True
• started: May 2, 2026
• availability: In Stock
• quantity: 3
• options: Ship-to-home
• sold: 0

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