From the J&P Cycles Blog Archive

It’s time for another edition of J&P Cycles Tech Talk. This time we'll be discussing Harley-Davidson ignitions. Our objective is to give a little history of what has been used in the past and give you some ideas of things to use to improve performance.

Harley-Davidson has used a variety of ignitions over the years. In the early days (prior to 1979) a points and condenser system with some type of advance was used. Prior to 1965, advancing and retarding the ignition was a manual thing controlled by the left handgrip. Many unsuspecting souls were pitched over their handlebars attempting to kick over a bike that didn't have the ignition retarded.

With the advent of electric start in 1965, automatic advance was developed. While the auto advance is very dependable, it is also high maintenance. With the points the rubbing block can wear away, material can transfer from one contact to the other, and the advance mechanism can wear out. These things will all hurt performance if not attended to.

In late 1979 Harley stepped into the electronic age with an ignition from Magnavox that eliminated the points and condenser, but retained the mechanical advance. This was a step in the right direction, but there were still some reliability issues with this system and it was not unusual for riders to have this system removed and the earlier points ignition system installed. The problems encountered here gave Harley's electronic ignition a bad name. It would take years for them to overcome this.

In 1982 the V-fire III ignition made its debut. This system is completely contained in a black box more commonly known as a module and the advance unit was eliminated because the module has a couple of advance curves built-in. Triggered by a rotor cup and a hall effect transducer, this system requires no maintenance. Due to the different ignition requirements presented by a light (Sporty) or a heavy (Dresser) motorcycle, a Vacuum Operated Electric Switch (VOES) that can be set at different vacuum levels handles changing the advance curves. Under heavy load conditions the ignition is retarded. This ignition soon proved to be very reliable but not the absolute best for performance.

All Harley ignitions that came direct from the factory prior to 1999 fired both spark plugs at the same time. One twin tower coil was triggered. One plug fires producing power, and the other plug fires during valve overlap. The “street” name for this type system is dual fire.

Finally some enterprising folks said “Let’s get rid of that wasted spark” and products were developed to do just that. (These dual points systems were the predecessor of today’s single fire system). The dual points single fire system was installed in the early Sixties by the Harley dealer network. The factory developed the parts, but would not install them, the dealer had to. The single fire that came later is where each cylinder fires independently of the other and the street name for this type ignition is appropriately single fire.

Crane, Dyna, & Spyke are companies that offer both single fire and dual fire ignitions. H-D itself has gone to the single fire type ignition on today’s TC88. Each brand of ignition has its advantages and disadvantages. A dual fire system is the same type that has been around forever and if you select one of this type, the coil that your bike currently has will usually do the job. But a single fire ignition has the advantage of better starting and reduced low speed vibration. These advantages are distinct and very noticeable. Its drawbacks are the increased initial cost and the requirement that a different type coil be purchased.

Crane, Spyke and the Dyna 2000 are true electronic ignitions that are a distinct improvement over the stock H-D module. The Dyna-S is very reliable and an improvement over stock but requires an advance weight set-up. Maintenance of the advance then rears its ugly head. Crane and Spyke do not require an advance weight set-up. Once they are set up and timed correctly they are truly set-and-forget type systems.

For those of you with a generator bottom end that desire the improvement given by lighting the fire more efficiently, J&P Cycles offers replacements for your points circuit breaker from Mallory and Spyke to take advantage of modern day technology.

Remember that to make power there are specific things we must do.

We can get more air (thus more fuel) in and out increasing volumetric efficiency. This is accomplished with carb and pipe changes.We can increase the quality of our ignition. This increases combustion efficiency. Note: Remember that by getting a more thorough burn, it’s not unusual to have to increase jet size (more fuel, more power) to take advantage of the improvement.

Generally the other two ways to make power (Mechanical and Thermal efficiency) are not practical for the street. If we get enough interest, maybe these are subjects for a future edition of Tech Talk.