Harley Davidson motorcycles are known for their powerful engines and iconic design. However, to keep a Harley running smoothly, it’s important to make sure the carburetor is properly tuned. One important aspect of carburetor tuning is jetting, which involves adjusting the size of the jets that control the flow of fuel and air into the engine.
For Harley CV carburetors, there are a variety of jetting options available depending on the specific model and modifications made to the engine. A Harley CV carb jetting chart can be a helpful tool for determining the appropriate jet size for a given setup. This chart provides a range of jet sizes based on factors such as engine displacement, exhaust system, and air intake configuration.
It’s important to note that jetting is not a one-size-fits-all solution, and the optimal jet size may vary depending on a number of factors. Additionally, improper jetting can lead to poor performance or even engine damage. Therefore, it’s recommended that jetting be performed by an experienced mechanic or with the guidance of a reputable tuning resource.
Understanding CV Carburetors
CV Carb Basics
CV carburetors, also known as Constant Velocity carburetors, are a type of carburetor commonly used in motorcycles. They are designed to maintain a constant velocity of air and fuel flow, which helps to provide a smooth and consistent ride.
One of the key features of a CV carburetor is the slide, which controls the amount of air entering the carburetor. As the throttle is opened, the slide is lifted, allowing more air to flow into the carburetor. This, in turn, allows more fuel to be drawn into the carburetor, resulting in increased engine power.
Components of Harley CV Carb
Harley CV carburetors are made up of several components, each of which plays a crucial role in the carburetor’s operation. Some of the key components include the slide, needle, jet needle, main jet, pilot jet, and choke.
The slide, as mentioned earlier, controls the amount of air entering the carburetor. The needle, which is attached to the slide, regulates the amount of fuel that is mixed with the air. The jet needle, which is located in the center of the needle, controls the amount of fuel that is drawn into the carburetor.
The main jet and pilot jet are responsible for regulating the amount of fuel that is mixed with the air. The main jet controls the amount of fuel that is mixed with the air at higher speeds, while the pilot jet controls the amount of fuel that is mixed with the air at lower speeds. The choke, which is located on the side of the carburetor, is used to help start the engine in cold weather.
Functionality of CV Carbs
CV carburetors are designed to provide a smooth and consistent ride, with a steady flow of air and fuel. They are also designed to be easy to tune and maintain, making them a popular choice among Harley riders.
When tuning a CV carburetor, it is important to understand the role that each component plays in the carburetor’s operation. By adjusting the main jet, pilot jet, needle, and other components, riders can fine-tune the carburetor to achieve optimal performance.
Overall, Harley CV carburetors are a reliable and efficient choice for motorcycle riders who value performance and consistency.
Preparing for Jetting
Before attempting to jet a Harley CV carburetor, it is essential to prepare adequately. This section will discuss the necessary tools and equipment and safety precautions to take before jetting.
Tools and Equipment
To jet a Harley CV carburetor, one needs a few tools and equipment. First, one needs a tuner’s kit, which usually includes various sizes of jets and needles. These can be obtained from a local motorcycle shop or online. Additionally, a screwdriver set is necessary to access the carburetor and adjust the jets. It is crucial to use the correct screwdriver to avoid damaging the carburetor’s screws.
It is also essential to have access to a factory service manual or an online manual. This manual provides detailed instructions on how to access the carburetor, remove it, and jet it. It also provides information on the correct jet sizes to use for different Harley models.
Safety Precautions
Jetting a Harley CV carburetor requires working with flammable materials. Therefore, it is essential to take safety precautions to avoid accidents. First, ensure that the motorcycle is in a well-ventilated area to avoid inhaling hazardous fumes. It is also essential to wear protective clothing, including gloves and goggles, to protect oneself from harmful chemicals.
Additionally, it is essential to disconnect the battery before attempting to jet the carburetor to avoid electrical shocks. Lastly, it is crucial to follow the instructions provided in the factory service manual or online manual to avoid damaging the carburetor or the motorcycle.
In conclusion, jetting a Harley CV carburetor requires adequate preparation, including having the necessary tools and equipment and taking safety precautions. It is essential to follow the instructions provided in the factory service manual or online manual to avoid damaging the carburetor or the motorcycle.
Jetting Fundamentals
When it comes to Harley CV carb tuning, understanding the fundamentals of jetting is essential. Jetting refers to the process of changing the size of the carburetor’s jets to achieve optimal fuel-air mixture.
Jet Size and Selection
Jet size is a crucial factor in carburetor jetting. The size of the jet determines the amount of fuel that flows through the carburetor. A larger jet size allows more fuel to flow, while a smaller jet size restricts fuel flow. When selecting a jet size, it’s important to consider factors such as altitude, ambient temperature, and engine modifications.
Main Jets and Their Role
The main jet is responsible for fuel delivery at higher engine speeds. Selecting the right main jet size is crucial for achieving optimal performance. A larger main jet size will provide more fuel at high speeds, while a smaller jet size will restrict fuel flow.
Pilot Jets and Idle Tuning
The pilot jet controls fuel delivery at idle and low engine speeds. The pilot jet size affects the air/fuel mixture at idle and low speeds. A larger pilot jet size will provide more fuel at idle, while a smaller jet size will restrict fuel flow. Tuning the pilot jet is essential for achieving smooth and stable idle performance.
In conclusion, understanding the fundamentals of jetting is crucial for Harley CV carb tuning. Proper jet selection and tuning can significantly improve engine performance and fuel efficiency. When selecting jet sizes, it’s important to consider factors such as altitude, ambient temperature, and engine modifications.
Adjusting the Mixture
Adjusting the mixture on a Harley Davidson CV carburetor is a simple process that can improve the performance of the motorcycle. There are two main ways to adjust the mixture: using the mixture screw or optimizing the fuel mixture.
Mixture Screw Tuning
The mixture screw, also known as the idle mixture screw or EZ-Just mixture screw, is located on the bottom of the carburetor. This screw controls the amount of fuel that is mixed with air at idle speeds. Adjusting the mixture screw can improve idle quality and throttle response.
To adjust the mixture screw, turn it clockwise to lean the mixture or counterclockwise to richen the mixture. Start by turning the screw in until it lightly seats, then turn it out 1.5 to 2 turns. Start the engine and let it warm up to operating temperature. Set the idle speed to the factory specifications and adjust the mixture screw until the highest idle speed is achieved.
Fuel Mixture Optimization
Optimizing the fuel mixture involves adjusting the main jet and slow idle jet to achieve the best performance. The main jet controls the fuel mixture at 3/4 to full throttle, while the slow idle jet controls the fuel mixture at idle to 1/4 throttle.
Harley carburetor jetting can be accomplished with minimal mechanical knowledge. However, it is important to note that main jet replacement should be reserved until after the slow idle jet is replaced and mixture is tuned unless a lean condition is apparent during full throttle.
In conclusion, adjusting the mixture on a Harley Davidson CV carburetor can improve the performance of the motorcycle. Using the mixture screw or optimizing the fuel mixture can both be effective ways to achieve this. It is recommended to consult a professional or refer to a Harley CV carb jetting chart for specific instructions and settings.
Fine-Tuning for Performance
Fine-tuning a Harley CV carburetor is a crucial step in achieving optimal performance. Once the carburetor is installed, the fine-tuning process begins. This process involves adjusting the accelerator pump and needle jet to achieve the best possible performance.
Accelerator Pump Adjustments
The accelerator pump is responsible for providing an extra shot of fuel when the throttle is opened quickly. This is important for performance, as it ensures that the engine receives enough fuel to accelerate quickly. Adjusting the accelerator pump nozzle is key to fine-tuning the carburetor for optimal performance.
To adjust the accelerator pump, one can remove the carburetor and use a workbench. First, remove the accelerator pump nozzle and check that it is clean and free of debris. If it is dirty, clean it with carburetor cleaner. Next, adjust the pump nozzle so that it sprays fuel for the correct duration. This duration can vary depending on the specific carburetor and engine setup.
Needle Jet and Midrange Tuning
The needle jet and midrange tuning are also important for achieving optimal performance. The needle jet controls the fuel mixture in the midrange, which is where the engine spends most of its time. Adjusting the needle jet can help fine-tune the carburetor for optimal performance.
To adjust the needle jet, one can start by replacing the Pilot Jet and only replace the Main Jet once the engine’s idle and midrange are satisfactorily tuned. The rule of thumb is to replace the Pilot Jet first and only replace the Main Jet once the engine’s idle and midrange are satisfactorily tuned.
In conclusion, fine-tuning a Harley CV carburetor is a crucial step in achieving optimal performance. Adjusting the accelerator pump and needle jet can help fine-tune the carburetor for optimal performance. By following these tips, one can ensure that their Harley is running at peak performance.
Troubleshooting Common Issues
Harley CV carburetors are known for their reliability and performance. However, even the best carburetors can experience issues from time to time. In this section, we will discuss some of the most common issues that riders may experience with their Harley CV carburetor and how to troubleshoot them.
Identifying Carburetor Problems
One of the most common issues with Harley CV carburetors is a poor idle or off-idle response. This can be caused by a variety of factors, including a dirty carburetor, clogged jets, or a faulty ignition system. To troubleshoot this issue, riders should first inspect their carburetor and ensure that it is clean and free of debris. They should also check their ignition system to ensure that it is functioning properly.
Another common issue that riders may experience is poor throttle response. This can be caused by a variety of factors, including a dirty or clogged carburetor, a faulty ignition system, or engine issues. To troubleshoot this issue, riders should first inspect their carburetor and ensure that it is clean and free of debris. They should also check their ignition system to ensure that it is functioning properly. If the issue persists, riders may need to address any underlying engine issues.
Solving Idle and Off-Idle Issues
If a rider is experiencing poor idle or off-idle response, there are several steps they can take to address the issue. First, they should inspect their carburetor and ensure that it is clean and free of debris. They should also check their ignition system to ensure that it is functioning properly. If these steps do not resolve the issue, riders may need to adjust their idle mixture or idle speed. This can be done by turning the idle mixture screw or the idle speed screw.
Addressing Full Throttle Challenges
If a rider is experiencing poor throttle response, there are several steps they can take to address the issue. First, they should inspect their carburetor and ensure that it is clean and free of debris. They should also check their ignition system to ensure that it is functioning properly. If these steps do not resolve the issue, riders may need to adjust their main jet or needle position. This can be done by referring to a Harley CV carb jetting chart and making the appropriate adjustments.
In conclusion, troubleshooting common issues with a Harley CV carburetor can be a simple process if riders follow the appropriate steps. By inspecting their carburetor and ignition system, adjusting their idle mixture or idle speed, and referring to a jetting chart to adjust their main jet or needle position, riders can ensure that their Harley is running smoothly and performing at its best.
Advanced Jetting Techniques
Experienced mechanics and tuners may need to use advanced jetting techniques to achieve optimal performance. Here are a few techniques to consider:
Non-Standard Applications
For non-standard applications, such as custom-built bikes or those with aftermarket parts, it may be necessary to experiment with different jet sizes to find the right balance of fuel and air. In these cases, it is important to keep in mind that changing the jet size will affect the air/fuel ratio and may require additional tuning.
Racing and High-Performance Tuning
For racing and high-performance applications, it may be necessary to use larger jets to provide more fuel to the engine. However, this can also result in decreased gas mileage and increased emissions. It is important to balance performance with environmental concerns and local regulations.
Experienced tuners may also experiment with different needle positions, which can affect the fuel flow at different throttle positions. Additionally, using a different needle taper can provide more precise control over the fuel flow.
Shovelheads and Non-Harleys
For older bikes, such as Shovelheads, it may be necessary to use non-standard jets or even custom-made jets to achieve optimal performance. It is important to consult with experienced mechanics and tuners to determine the best jetting options for these types of bikes.
For non-Harleys, such as Japanese or European bikes, it may be necessary to use non-standard jets or even modify the carburetor to achieve optimal performance. Again, it is important to consult with experienced mechanics and tuners to determine the best jetting options for these types of bikes.
Overall, advanced jetting techniques require a combination of experience, knowledge, and experimentation. It is important to keep in mind that changing the jet size will affect the air/fuel ratio and may require additional tuning. Additionally, it is important to balance performance with environmental concerns and local regulations.
Support and Resources
Utilizing Online Forums
Harley riders can find a wealth of information on online forums. These forums are a great place to get advice and tips on jetting their CV carburetors. There are many forums out there, but some of the most popular ones include V-Twin Forum, Harley Davidson Forums, and HD Forums.
On these forums, riders can ask for repair advice, technical assistance, and even find service manuals. They can also find discussions on jetting their CV carburetors. Many experienced riders are willing to share their knowledge and help others with their carburetor issues.
Professional Tuning Assistance
For those who prefer professional tuning assistance, there are many options available. Harley dealerships offer tuning services, and there are also independent shops that specialize in tuning Harley carburetors.
One such option is CV Performance, which offers a Tuners Kit that can bring out the true performance of your Harley CV carburetor. The kit comes with detailed instructions, and there are also video instructions available online.
Another option is to find a reputable Harley tuner in your area. These professionals have the experience and knowledge to tune your carburetor to perfection. They can also provide advice on jetting and other performance upgrades.
In conclusion, riders have many options when it comes to getting support and resources for jetting their Harley CV carburetors. Whether they choose to utilize online forums or seek professional tuning assistance, there is no shortage of information available. With a little research and some expert advice, riders can achieve optimal performance from their carburetors.