Frequently Asked Questions (FAQs)
1. What year did Harley start using the CV carburetors?
Harley-Davidson started using the CV carburetors on 1989 Sportsters and 1990 Big Twins. These carburetors were considered decent in stock form, despite some opinions from magazine writers and engine tuners.
2. How do I identify my Harley-Davidson carburetor?
To identify a Harley-Davidson carburetor, look for a code on one side, above the float bowl. This code consists of two parts: the first four characters are the 'Set Mark' for internal HD use, and the next letter represents the revision code.
3. What are the advantages of a CV carburetor?
CV carburetors offer several advantages. They allow for more precise metering, resulting in a less boggy engine under load conditions. With a CV carburetor, you can open the throttle wide without losing power. These benefits contribute to better performance and throttle response.
To determine the appropriate carburetor for your needs, you can use a basic formula. Multiply the engine displacement by the maximum RPM and divide the result by 3,456. For example, a 355ci small-block with a 6,000-rpm max engine speed would work well with a 616-cfm carburetor ((355 x 6,000) / 3,456 = 616.32). This calculation helps match the carburetor to your engine's requirements.
5. How do I know what carburetor to buy?
The carburetor CFM size is determined by the engine size, the maximum RPM the engine will be used at, and the main purpose of the vehicle (street or race use). You can calculate the CFM size using the formula: (engine cubic inches) x (max engine RPM) x volumetric efficiency. This calculation helps ensure you select the appropriate carburetor for your specific needs.
6. How do I know what carburetor to use?
To determine the most appropriate carburetor for your needs, you can use a basic formula. Multiply the engine displacement by the maximum RPM and divide the result by 3,456. This calculation helps match the carburetor to your engine's requirements, ensuring efficient and effective performance.