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How to Convert a Carbed Motorcycle to EFI

by William Machin

Electronic fuel injection (EFI) consists of throttle bodies that take the place of the carburetors, the ECU computer and special sensors. The ECU computer makes fuel calculations based on inputs from sensors on the engine and at the throttle bodies. In most cases, a high-output fuel pump is needed to meet the demands of the system. Installation takes mechanical expertise, knowledge of your motorcycle and experience interpreting electrical wiring diagrams. However, it is possible to obtain an EFI kit and fuel pump from a motorcycle accessory outlet and convert a carbed motorcycle to EFI. The instructions below provide general guidelines for converting to EFI, but the specifics will vary slightly based on the year, make and model of the motorcycle.

Remove the rider's seat. Disconnect the battery cables from the battery. Turn the fuel petcock off. Disconnect the fuel line from the petcock and remove the gas tank.

Disconnect the throttle linkages and the fuel lines at the carburetors. Remove the carburetors. Detach and label the electrical wires from the fuel pump. Remove the fuel pump and the attached fuel lines.

Locate the ignition circuit wire connector in the main wiring harness of the motorcycle. Remove the stock connector and attach the new connector from the EFI kit. Route the wires to a mount for the ECU computer. Attach the universal bracket from the kit if a mount is not part of the motorcycle. Route the wires to the bracket.

Refer to instructions in the EFI kit. Install the oxygen sensor at the #1 cylinder on the engine. Route the sensor wire to the mount or bracket for the ECU computer.

Install the intake air sensors and throttle position sensors onto the new EFI throttle bodies. Mount the throttle bodies on the intake manifolds at the cylinder heads. Route the wires from the sensors to the mount or bracket for the ECU.

Attach the ECU to the mount or the universal bracket. Refer to the instructions and color codes in the wiring diagram and connect the oxygen sensor, intake air sensor and throttle position sensor wires to the ECU.

Mount the high-output fuel pump at the mount where the old pump was removed. Connect the provided fuel lines at the pump and the throttle bodies as described. Connect the labeled electrical leads to the appropriate terminals on the fuel pump.

Reattach the throttle linkages to the new throttle bodies with the provided clips and keepers. Twist the throttle grip as you adjust the linkages so both engage simultaneously at each throttle body.

Mount the gas tank on the motorcycle. Connect the fuel line from the petcock to the new fuel pump with the provided clamp. Reconnect the battery cables.

Tip

  • It might be necessary to install compatible cylinder heads with some conversions. Always review the instructions thoroughly before purchasing or installing EFI systems.

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About the Author

William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.

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