KEIHIN 019-813 Jet Carburetor N424-25B

( Brand: Keihin ), ( Manufacturer Part Number: 019-813 ), ( Part Type: Jet Carburetor ), ( Country Of Origin: Us ), ( Item Length: 4.000 ), ( California Prop 65 Warning: Warning )

Review KEIHIN Jet 42 Oem Carburetor Replacement fits PILOT

The **Keihin N424-25B Pilot Jet 42** carburetor is a precision-engineered component designed to deliver optimal performance and reliability for high-performance motorcycles, particularly those equipped with Keihin s advanced fuel injection systems or standalone carbureted engines. This jet, identified by its designation **019-813**, is a critical part of the **Pilot Jet 42 series**, a line of high-flow, high-efficiency jets engineered to enhance throttle response, fuel economy, and overall engine efficiency across a wide range of riding conditions. Crafted from durable, corrosion-resistant materials, the N424-25B jet is built to withstand the demands of aggressive riding, high-speed cruising, and extreme temperatures, ensuring consistent performance even under the most challenging circumstances. Its design incorporates a **precision-machined needle and seat assembly**, allowing for fine-tuned fuel delivery and air-fuel mixture control, which is essential for maintaining peak engine power while minimizing emissions and fuel waste. Whether installed on a sportbike, cruiser, or off-road motorcycle, this jet is engineered to work seamlessly with Keihin s **CV carburetors** or **Pilot Jet systems**, providing a balance between power output and fuel efficiency that appeals to both street riders and enthusiasts seeking a refined, high-performance experience. The **N424-25B** is particularly favored by tuners and mechanics for its adaptability, as it can be easily adjusted to suit different fuel types, altitudes, and engine modifications, making it a versatile choice for both stock and modified setups. Built to Keihin s exacting standards, this jet exemplifies the brand s commitment to innovation and performance, ensuring that riders can trust it to deliver consistent, reliable power with every rev of the engine.

### Pros and Cons of buying a Keihin 019-813 N424-25B Pilot Jet (42 Carburetor)

1. **High Performance and Reliability** The Keihin N424 carburetor is widely regarded as one of the best in its class, known for delivering strong throttle response, smooth power delivery, and consistent performance across a wide RPM range. It is a favorite among professional racers and tuners for its precision engineering.

2. **Durability and Build Quality** Keihin carburetors are built with high-quality materials, including precision-machined components and durable seals. The N424 model, in particular, is designed to withstand high stress, making it suitable for aggressive driving and racing applications.

3. **Adjustability and Tuning Flexibility** The carburetor features a modular design with easily replaceable jets (including the pilot jet you re considering, the 42). This allows for fine-tuning of fuel mixture, air-fuel ratio, and performance characteristics to match specific engine setups, fuel types, or track conditions.

4. **Compatibility with High-Performance Engines** The N424 is designed for high-revving, high-power engines, making it a popular choice for modified street cars, drift cars, and race engines. It pairs well with turbocharged and naturally aspirated setups when properly tuned.

5. **Aftermarket Support and Availability** Keihin is a well-established brand with a strong aftermarket presence. Parts, tuning guides, and support are widely available, making it easier to troubleshoot issues or upgrade components as needed.

6. **Fuel Efficiency and Cold Start Performance** The pilot jet (42 in this case) plays a crucial role in idle and low-RPM stability. A properly sized pilot jet ensures smooth idling, better cold starts, and reduced fuel waste, which is beneficial for both performance and longevity.

7. **Long-Term Value** While the upfront cost may be higher than some alternatives, the longevity and performance of a Keihin carburetor often justify the investment, especially for enthusiasts who plan to keep their car modified for years.

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1. **High Initial Cost** Keihin carburetors, including the N424, are significantly more expensive than basic or entry-level carburetors. The full setup (including the pilot jet) can be a substantial investment, especially for hobbyists or those on a tight budget.

2. **Complexity and Tuning Requirement** Unlike simpler carburetors, the N424 requires careful tuning to avoid issues like rich or lean mixtures, which can damage the engine if not properly adjusted. This may involve purchasing additional tools (like a dyno or exhaust gas analyzer) and spending time learning the tuning process.

3. **Maintenance Demands** Carburetors, in general, require more frequent maintenance than fuel-injected systems. The N424 is no exception it needs regular cleaning, jet adjustments, and seal replacements to prevent clogging, leaks, or performance degradation. Neglecting maintenance can lead to poor performance or engine damage.

4. **Fuel Quality Sensitivity** Carburetors are highly sensitive to fuel quality. Poor-quality fuel or contaminants can clog jets (including the pilot jet) quickly, leading to performance issues. This requires using high-quality fuel and potentially adding fuel additives to keep the carburetor clean.

5. **Learning Curve for Installation** Installing a Keihin N424 carburetor is not a beginner-friendly task. It requires mechanical skill, patience, and often the help of a professional. Improper installation can lead to leaks, vacuum issues, or even engine damage.

6. **Potential for Pilot Jet Clogging** The pilot jet (42) is a small, precision part that can easily become clogged with dirt, varnish, or debris over time. If not cleaned or replaced regularly, it can cause idling problems, stalling, or rough operation, requiring frequent maintenance.

7. **Limited Use for Stock or Mildly Modified Engines** If you re running a stock or lightly modified engine with no performance goals, the N424 may be overkill. A simpler carburetor or even fuel injection might be more practical and cost-effective for such applications.

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The Keihin 019-813 N424-25B carburetor with the 42 pilot jet is an excellent choice for enthusiasts seeking high performance, reliability, and tunability in a modified or race-oriented engine. Its superior build quality, adjustability, and reputation in the performance community make it a top-tier option for those willing to invest the time and effort into tuning and maintenance.

However, it is not the best fit for everyone. The high cost, complexity, and maintenance demands may outweigh the benefits for casual drivers, stock cars, or those new to carburetor tuning. If your primary goal is reliability without deep modification, alternatives like simpler carburetors or fuel injection might be more practical.

- **Buy it if:** You are running a high-performance or race engine, have experience (or are willing to learn) with carburetor tuning, and prioritize power, precision, and long-term reliability. The 42 pilot jet is a good starting point for idle and low-RPM stability, but ensure it matches your engine s fuel mixture requirements.

- **Avoid it if:** You are on a tight budget, lack mechanical experience, or are not committed to regular maintenance. In such cases, consider a more affordable carburetor or fuel injection for a simpler, more low-maintenance solution.

For the best results, pair this carburetor with high-quality fuel, a proper tuning process, and regular maintenance. If possible, consult with a carburetor specialist or tuner to ensure the pilot jet and other jets are correctly sized for your specific engine setup.

Details:

Features: Keihin N424-25B series Pilot jet. Built for consistent fuel metering and reliable tuning, it is ideal maintenance, repair, or performance setup. Menu Keihin N424-25B Pilot Jet 42 OEM 019-813 Carburetor Replacement: Series Jet: This Pilot jet is a quality aftermarket replacement designed for carburetors. Precision-machined brass construction.

High quality aftermarket replacement part. Note: Please verify part number and application before purchase to ensure proper fit function. Untitled Document. Supports smooth idle and low-throttle fuel delivery.

Single unit listing: 1 jet included.

part #: 019813 prices

• $18.40-$24.99

specifications intakefuelmotorcycle:

• for models: Pilot
• brand: Keihin
• mpn: 019-813
• part type: Jet Carburetor
• country of origin: Us
• item length: 4.000
• california prop 65 warning: Warning

offer intakefuelmotorcycle:

• quantity: 1
• sold: 0
• options: Ship-to-home
• started: April 5, 2026
• availability: In Stock

seller intakefuelmotorcycle:

• # reviews: 50074
• rating: 99.4%
• city: Midvale, Utah

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• type: Fixed
• cost: $0.00
• class: Expedited

general intakefuelmotorcycle:

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

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• other

returns intakefuelmotorcycle:

• policy: Returns Accepted
• time: 30 Days
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