Harley Davidson is a world-famous motorcycle company, running since 1902. They have evolved a lot since the last century.

One of the changes they have made is the replacement of the original equipment with the Hi-4 Ignition system.

Let us learn more about this in the article below.

History of Hi-4 Ignition System

The Hi-4 ignition system was introduced in 1978 and there are later models as well. The Hi-4 ignition system is used only for off-road biking and early original equipment points application.

The Hi-4 ignition system is street legal in 50 states according to the California Air Resources Board E.O. D-225-43.

Here are the applications that are feasible:

1984-93 FX Models

1985-93 FX Models 1986-93 FX Models

Advantages of Using the Hi-4 Ignition System

The Hi-4 uses Single fire race ignitions that are known as true single fires, even when they are cranking the speed. Every cylinder will be fired independently and only on the compression stroke.

This single fire will increase the output of the engine when fired at high RPMs. This improves starting and the probability of backfiring at high RPMs is greatly reduced.

Two starting modes are provided, one with the kick start and the other is the electric start. A tach output makes sure that accurate tach readings are taken even when at the rev limit.

Disadvantages of the Hi-4 Ignition System

Additional parts are required to install this ignition system. The original equipment timing rotor will be required for FL series big twin models that were launched before 1985.

This makes it very expensive and even replacing it is not cost-effective.

It will also be required for FX series big twin and XL series Sportster models prior to 1984. And for all models with OE points. This part is not included in the kit and will have to be purchased from a local dealer.

In the 1996 models and later there is a vehicle tilt sensor that shuts off the ignition if the motorcycle rolls on one side. This feature gets disabled when the Hi-4 ignition is installed.

This ignition system is not recommended if the motorcycle is not going to be used for off-road racing. The fuel consumption is very high and such a high power output from the engine is not recommended for everyday use.

Installation Issues

In certain cases when the installation is not proper, the ignition system can sometimes cause interference with the electronic ignition system and/or accessories.

The installation of Hi-4 is very difficult. The wires must be of a certain quality. Like cranes,   firewire spiral cores are recommended for use in Hi-4 ignition with dual plug heads.

Even the removal of the electronic ignition system can be a little tricky. It requires precise work which requires the help of a professional.

Coils used with Hi-4 must have at least 2 ohms of primary resistance. Coils of 4 ohms or above might be used but they are not going to give optimum output.

Removal of the electronic ignition system differs in 1970-1977 and 1978-1979 models.


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