S&s Super E Accelerator Pump Diagram

The S&S Super E carburetor is a popular choice for Harley-Davidson enthusiasts and custom bike builders alike. Its simplicity and performance are well-regarded, but understanding its inner workings is crucial for proper tuning, maintenance, and troubleshooting. This article focuses on the accelerator pump diagram of the Super E, providing a detailed breakdown for experienced DIYers.

Purpose of the Accelerator Pump Diagram

The accelerator pump diagram is your roadmap to understanding how the accelerator pump system functions within the Super E carburetor. Having this diagram readily available is vital for several reasons:

Repair and Overhaul: When rebuilding or repairing your Super E, the diagram shows the correct placement of each component, including springs, check valves, and diaphragms.
Troubleshooting: Diagnose issues such as hesitation or bogging during acceleration. By understanding the flow of fuel in the accelerator pump circuit, you can pinpoint potential problems like a clogged nozzle or a leaky diaphragm.
Tuning: While the diagram doesn’t directly detail tuning adjustments, understanding how the accelerator pump works helps you make informed decisions when adjusting the idle mixture and intermediate jets.
Learning: Deepen your understanding of carburetor function in general. The Super E's accelerator pump provides a relatively simple yet effective example of this crucial system.

Key Specs and Main Parts

Before diving into the diagram, let's review the main components of the Super E's accelerator pump system and their functions:

Accelerator Pump Diaphragm: A flexible membrane that, when actuated, displaces fuel into the carburetor's venturi.
Accelerator Pump Lever: Mechanically linked to the throttle shaft. As the throttle is opened, the lever pushes on the diaphragm rod.
Diaphragm Rod: Transfers the motion of the lever to the diaphragm.
Accelerator Pump Nozzle (Discharge Nozzle): Delivers the squirt of fuel into the carburetor's venturi, enhancing fuel delivery during rapid throttle opening. Usually located near the booster.
Check Valves: Small valves that allow fuel to flow in only one direction, ensuring proper charging and discharging of the accelerator pump circuit. Often a ball-and-spring design.
Fuel Reservoir (Well): Holds the fuel that is delivered by the accelerator pump. This is fed by the float bowl.
Springs: Control the return of the diaphragm and the action of the check valves.

Key Specifications: The exact specifications of the accelerator pump system, such as diaphragm size and nozzle diameter, can vary slightly depending on the specific Super E model and year. However, the fundamental operating principle remains the same. It's essential to refer to the specific documentation for your carburetor model when ordering replacement parts.

Symbols and Diagram Interpretation

The S&S Super E accelerator pump diagram typically uses standard symbols to represent different components and functions. Here's a breakdown:

Solid Lines: Represent fuel passages within the carburetor body. The thickness of the line may sometimes indicate the size of the passage.
Dashed Lines: Can represent mechanical linkages, such as the accelerator pump lever connecting to the throttle shaft.
Circles and Spheres: Often represent check valves (especially ball-type check valves).
Springs: Depicted as coiled lines, indicating their role in providing resistance and returning components to their original position.
Diaphragms: Shown as a thin, flexible membrane, often with a shaded area to indicate its cross-section.
Arrows: Indicate the direction of fuel flow through the passages and check valves.

Understanding the Flow: Pay close attention to the arrows indicating fuel flow. Trace the path of fuel from the float bowl, through the check valves, into the accelerator pump well, and out through the discharge nozzle. This will give you a clear understanding of how the system operates.

How the Accelerator Pump Works

The accelerator pump is designed to overcome the temporary lean condition that occurs when the throttle is opened rapidly. Here's a step-by-step explanation of how it works:

Throttle Opening: As you twist the throttle, the throttle shaft rotates.
Lever Actuation: The accelerator pump lever, connected to the throttle shaft, is pushed forward.
Diaphragm Displacement: The lever pushes on the diaphragm rod, which in turn pushes on the accelerator pump diaphragm.
Fuel Injection: The diaphragm's movement forces fuel from the accelerator pump well, through a check valve, and out through the accelerator pump nozzle into the carburetor's venturi. This short burst of fuel enriches the air-fuel mixture, preventing a lean stumble.
Diaphragm Return: When the throttle is held steady or returned to idle, a spring pushes the diaphragm back to its original position, drawing fuel from the float bowl through another check valve to refill the accelerator pump well, ready for the next acceleration.

The key is that the accelerator pump provides a temporary enrichment. It is not intended to sustain the richer mixture for extended periods. It's a supplemental system, not a replacement for proper jetting.

Real-World Use: Basic Troubleshooting

Here are some common problems related to the accelerator pump system and how the diagram can help you diagnose them:

Hesitation or Bogging During Acceleration: This is the most common symptom of an accelerator pump issue.
- Possible Causes: Clogged accelerator pump nozzle, leaky diaphragm, stuck or malfunctioning check valves, insufficient fuel level in the float bowl.
- Using the Diagram: Check the fuel flow path from the float bowl to the nozzle. Disassemble the nozzle and check for blockages. Inspect the diaphragm for tears or cracks. Ensure the check valves are moving freely and sealing properly.
Excessive Fuel Consumption: A leaking accelerator pump can constantly inject fuel into the venturi, leading to poor fuel economy.
- Possible Causes: Leaky diaphragm, malfunctioning check valves.
- Using the Diagram: Carefully inspect the diaphragm for leaks. Check the check valves to ensure they are seating properly and not allowing fuel to flow backwards into the fuel well.
No Acceleration Enrichment (No "Squirt"): If the accelerator pump isn't delivering any fuel, the engine will stumble badly when the throttle is opened.
- Possible Causes: Severely clogged nozzle, completely ruptured diaphragm, stuck check valves, disconnected or broken linkage.
- Using the Diagram: Trace the entire system from the throttle linkage to the nozzle. Start with the nozzle and work backwards looking for the blockage.

Safety Considerations

Working with carburetors involves handling gasoline, which is extremely flammable. Here are some important safety precautions:

Work in a well-ventilated area: Avoid inhaling fuel vapors.
No open flames or sparks: Gasoline vapors can ignite easily.
Disconnect the battery: Prevent accidental sparks.
Dispose of fuel properly: Do not pour gasoline down drains or onto the ground.
Wear safety glasses: Protect your eyes from fuel splashes and debris.

Special Note on the Accelerator Pump Nozzle: The accelerator pump nozzle is a small, precise component. Be extremely careful when cleaning it. Avoid using hard or abrasive tools that could damage the orifice. Carburetor cleaner and compressed air are typically sufficient.

Remember: When dealing with the small parts in the carburetor's accelerator pump system, use good lighting, and be careful not to lose any pieces. A clean workspace will also help to ensure no dirt or debris is introduced into the system during reassembly.

We have a high-resolution version of the S&S Super E accelerator pump diagram available for download. This will provide you with a more detailed visual reference for your repairs and troubleshooting. Contact us to receive the file.