How to Rejet Harley Davidson Carburetor for Improved Performance and Fuel Efficiency

Ever wondered why your Harley isn’t running as smoothly as it used to? If you’ve noticed rough idling or poor acceleration, it might be time to consider rejetting your carburetor. This common issue affects many riders, but the good news is you can fix it yourself with a bit of guidance.

Key Takeaways

• Understanding Carburetors: Familiarize yourself with the two main types of Harley Davidson carburetors, CV and Bing, as these dictate your rejetting approach.
• Common Performance Issues: Recognize issues such as rough idling, poor acceleration, and backfiring, which can often be fixed through proper rejetting.
• Importance of Rejetting: Rejetting can significantly enhance performance by optimizing fuel-air mixtures, resulting in improved throttle response, smoother acceleration, and better fuel efficiency.
• Essential Tools for Rejetting: Gather necessary tools, such as screwdrivers, wrenches, and jet kits, to ensure a smooth rejetting process.
• Step-by-Step Process: Follow a clear guide to carefully remove the carburetor, choose the right jet size, install new jets, and make necessary adjustments for optimal performance.
• Testing and Adjustments: After rejetting, perform a thorough engine test and make adjustments to idle and jet sizes to perfect your Harley’s performance.

Understanding Harley Davidson Carburetors

Harley Davidson carburetors play a crucial role in your bike’s performance. Knowing how they function helps you troubleshoot issues and optimize performance effectively.

Types of Carburetors

Harley Davidson primarily uses two types of carburetors:

• CV Carburetors: Constant Velocity carburetors adjust the fuel-air mixture automatically. This type provides smoother acceleration and is common in newer models.
• Bing Carburetors: Found on older models, Bing carburetors operate differently and require manual tuning for efficient performance.

Each type serves different Harley models. Knowing which carburetor your bike has informs your rejetting approach.

Common Issues with Factory Jetting

Factory jetting might lead to several problems. Here are the most common issues:

• Rough Idling: Improper fuel-air mixture can cause inconsistent engine idle. Adjusting the jets can address this problem.
• Poor Acceleration: A rich or lean mixture affects throttle response. Rejetting can enhance acceleration and overall performance.
• Backfiring: Excess fuel in the exhaust might lead to backfiring during deceleration. Correct jetting reduces this issue.

Identifying these issues early can save you time and improve your riding experience.

Why Rejetting is Important

Rejetting your Harley Davidson carburetor significantly enhances your bike’s performance. Properly adjusted carburetors ensure optimal fuel and air flow, addressing common riding issues.

Improving Performance

Rejetting improves performance by optimizing the fuel mixture. A richer mixture results in better combustion, leading to smoother acceleration and improved throttle response. For example, if your Harley struggles during climbs, rejetting can provide the extra power needed. Adjusting jet sizes can also reduce backfiring, enhancing overall performance during rides.

Enhancing Fuel Efficiency

Rejetting enhances fuel efficiency by ensuring the engine receives the right fuel-air ratio. Too much fuel can lead to inefficient combustion, wasting fuel. Conversely, providing the right mixture ensures better fuel burn. For instance, riders have reported fuel savings of up to 10-15% after proper rejetting. By fine-tuning your carburetor, you save money at the pump while enjoying longer rides.

Tools and Materials Needed

You’ll need specific tools and materials to rejet your Harley Davidson carburetor effectively. This section outlines what you require to make the process smooth and efficient.

Essential Tools

1. Screwdrivers – Flathead and Phillips screwdrivers for removing carburetor components.
2. Wrenches – A set of metric wrenches to loosen and tighten bolts.
3. Pliers – Needle-nose pliers for grasping and pulling small fittings.
4. Jet Tool – A jet screw tool for adjusting needle jet settings precisely.
5. Fuel Line Pliers – For disconnecting fuel lines without damage.
6. Shop Towels – To clean up fuel spills and keep the workspace tidy.
7. Torque Wrench – To ensure bolts are tightened to the manufacturer’s specifications.

1. Dynojet Jet Kit – Offers essential jets, springs, and instructions for precision tuning. Ideal for various Harley models.
2. Keith Black Jet Kit – Includes multiple jet sizes and enhances throttle response. Excellent for performance upgrades.
3. Vance & Hines Jet Kit – Specifically designed for cruisers, improving engine performance while maximizing fuel efficiency.
4. S&S Carburetor Jet Kit – Provides a comprehensive set of jets suitable for S&S carburetors, enhancing horsepower and torque.
5. Keihin Jet Kit – Tailored for Keihin carburetors, ensuring optimal performance without exhaust modification.

Gathering these tools and materials sets you up for success in achieving improved performance from your Harley’s carburetor.

Step-by-Step Guide to Rejetting

Rejetting your Harley Davidson carburetor can significantly boost its performance. This guide breaks down each step you need to follow.

Preparing Your Motorcycle

1. Gather Tools: Ensure you have the necessary tools like screwdrivers, wrenches, and a socket set. A torque wrench helps with reinstallation.
2. Choose a Workspace: Select a clean, well-lit area to work on your motorcycle. Avoid areas with moisture or extreme temperatures.
3. Turn Off Fuel Supply: Shut off the fuel valve to prevent spills during the process.

Removing the Carburetor

1. Loosen the Air Cleaner: Unscrew the air cleaner cover and detach it, making access easier.
2. Detach Throttle Cables: Carefully disconnect throttle cables from the carburetor by loosening their screws.
3. Unbolt the Carburetor: Locate and remove the mounting bolts securing the carburetor to the engine. Gently pull the carburetor away.

Choosing the Right Jet Size

1. Consult Your Manual: Refer to the motorcycle’s service manual for jet size specifications tailored to your model.
2. Evaluate Performance Needs: Consider your riding style and conditions, such as elevation and temperature. For example, higher altitudes may require smaller jets.
3. Select Jet Kits: Use reputable brands that offer kits designed for your Harley model to ensure compatibility.

Installing the New Jets

1. Open the Carburetor: Remove the float bowl by unscrewing the screws. Carefully lift it off without damaging gaskets.
2. Remove Existing Jets: Unscrew the old jets with a flat-head screwdriver. Take care not to strip the screw heads.
3. Install New Jets: Screw in the new jets securely. Use a torque wrench if the manual specifies a torque setting to prevent leaks.

1. Reattach the Float Bowl: Place the float bowl back on, aligning it with the gaskets. Secure it with screws.
2. Reconnect Cables: Attach the throttle cables, ensuring they operate smoothly without binding.
3. Mount the Carburetor: Bolt the carburetor back into place on the engine. Follow the torque setting from your manual for precision.

Testing and Final Adjustments

Testing and making adjustments to your Harley Davidson’s carburetor after rejetting ensures optimal performance. Follow these guidelines for effective testing and fine-tuning.

How to Test Your Changes

1. Start the Engine: Begin with a cold start to check for smooth ignition and warm up the engine. Listen closely to the idle sound.
2. Take a Test Ride: Ride for about 10-15 minutes at varying speeds. Pay attention to acceleration, responsiveness, and any stalling.
3. Check for Backfiring: Accelerate quickly and decelerate to identify any backfiring issues, indicating a potentially lean mixture.
4. Monitor Performance: Assess throttle response and overall power. Performance should feel improved compared to before rejetting.
5. Inspect Fuel Consumption: Note fuel usage during the test ride. An excessive increase may point to a rich mixture.

1. Adjust the Idle Mixture: Use a screwdriver to tweak the idle mixture screw. Turn it counterclockwise slightly to enrich the mixture or clockwise to lean it out.
2. Test the Mid-Range: Maintain steady acceleration in the mid-range and adjust the main jet if needed. If the engine stutters, it may require a larger jet.
3. Refine the Pilot Jet: If the bike doesn’t idle smoothly, consider changing the pilot jet and making subtle adjustments.
4. Re-check After Changes: Repeat the testing process after any adjustments. Thorough testing ensures the settings are correct.
5. Consult Professionals if Needed: Don’t hesitate to seek expert advice if performance issues persist despite your adjustments.

These steps help you achieve the best performance from your Harley Davidson after rejetting the carburetor.

Conclusion

Rejetting your Harley Davidson carburetor can breathe new life into your ride. By following the steps outlined and making the right adjustments you’ll notice improved throttle response and better fuel efficiency.

Don’t hesitate to experiment a bit with your settings to find that sweet spot that works best for your bike. Remember that fine-tuning might take some time but it’s worth it for that smooth ride you crave.

If you ever feel unsure just reach out to a professional or fellow riders for advice. Enjoy the open road and the thrill of a well-tuned Harley!

Frequently Asked Questions

What are common performance issues for Harley riders?

Harley riders often face issues like rough idling and poor acceleration. These problems can typically arise from an improperly tuned carburetor, which can affect overall ride quality and engine performance.

Why is rejetting the carburetor important for Harley Davison?

Rejetting the carburetor is essential to optimize the fuel mixture for improved performance. It enhances throttle response, increases fuel efficiency, and helps resolve common idling and acceleration issues.

What’s the difference between CV Carburetors and Bing Carburetors?

CV Carbs, or Constant Vacuum Carbs, maintain a constant vacuum for better performance and fuel efficiency. Bing Carbs are known for their simplicity and reliability but may require different tuning approaches compared to CV Carbs.

How do I prepare for rejetting my Harley’s carburetor?

To prepare for rejetting, ensure your motorcycle is on a stable surface. Gather the necessary tools, including carburetor jets, screwdrivers, and a clean workspace. Familiarize yourself with the carburetor’s components before starting.

What are the steps to rejet my Harley’s carburetor?

1. Prepare the motorcycle and workspace.
2. Remove the carburetor carefully.
3. Choose the appropriate jet size based on performance needs.
4. Install the new jets and reassemble the carburetor.

How can I test my Harley after rejetting?

After rejetting, start the bike and allow it to warm up. Test the throttle response and acceleration. Adjust the idle mixture as needed. If the performance isn’t satisfactory, revisit your jet choices or consult a professional.

When should I consult a professional for rejetting?

If you’re unsure about the rejetting process or don’t see the desired improvements, it’s best to consult a professional. They can provide expert advice and ensure your Harley is running at peak performance.