Harley-Davidson ignition installation and adjustment

A little theory
In the motorcycle engine there are 2 fundamental systems that allow its operation: the feed system, which provides the air-icasoline mixture in the exact quantity and conditions for a good combustion and the ignition system, which produces The spark that will cause this combustion at the right time. The spark plug burns the mixture, is exploding and an increase in temperature and pressure in the combustion chamber (between the cylinder and the butt) because the gases expand quickly, which causes the movement of the piston.
It is very important that the spark occurs at a very specific moment so that the greatest gas expansion occurs when the piston is in the upper dead point (PMS), to make the most of the explosion.

As the piston rises and lowers very fast and the mixture needs some milliseconds to complete complete possible. This is called "ignition advance." The advance varies depending on the revolutions and motor load. If the ignition is very advanced, the expansion of gases will occur when the piston is still rising, which will cause the "chopped" or piston of the piston, something that can destroy an engine in seconds. If the advance is very delayed we will lose efficiency in the engine, and our fuel consumption will be high. Then we will see how to adjust the ignition at its ideal point.

Single Fire and Dual Fire
Explained in a simple way, the ignition system has a magnetic sensor that captures a signal when the crankshaft rotates, and therefore knows where the piston is. At the exact moment the coil circuit opens, and through it a current is sent through the high voltage cable to the spark plug, which produces the spark.
In Harley-Davidson models prior to the year 2000 (Sportster prior to 2004) the coil produces a spark at the same time in the 2 spark plugs, which is known as Dual Fire. With this system only one of the 2 sparks is used, since only 1 cylinder is prepared for combustion at all times.
During this time there were Single Single Fire Lowering Systems, derived from the competition, which only produce the spark in 1 spark plug each time, with which it is more powerful, and combustion occurs in a more effective way. This system is currently the employee in all HD models.

Hands to work
We will proceed to the installation of a complete ignition system, to update a Dual Fire system to the most modern and efficient Single Fire. This system also has the advantage of being programmable, so we can choose several ignition curves, motor revolutions limit, pedal or electric and use of street or competition. Perfect!
The system consists of a rotor attached to the crankshaft, the electronic module with its adjustment dish, the coil and the high voltage cables.

The installation is quite simple, we begin by removing the current system following the service manual and the instructions of the kit manufacturer. Then we drill the rivets of the sensor cover, remove the same, and change the rotor for the new one.

We install and connect all the wiring following the instructions, it is very important that the connections are well welded and finished, because the reliability of our system will depend on this.

Then we place the ignition module in its accommodation and hold it with the 2 screws that will allow us to adjust it along the oval holes carried by the adjustment plate. After reading the instructions carefully we select with the switches the parameters (ignition curve, RPM limit ...) appropriate to our configuration.

Ignition adjustment
We are now with the most interesting and critical phase of the process, where we will regulate the advance of our engine. To perform this task we will need a Stroboscopic gun (emite una luz cada vez que se produce una chispa en la bujía) y un Transparent plug To be able to see the progress brand.

The first thing we will do will be to remove the plug between the 2 bases of the cylinders, to be able to see the crankshaft progress marks. It is important to know what the exact brands of our year and model are, based on the service manual.

After disassembling the spark plugs and groaning a march we turn the rear wheel until we can see through the hole the brand of the crankshaft, and focus this mark on the window.

Then we slightly loosen the screws that hold the ignition dish and we slowly move it until the LED that has incorporated is turned off. In this precise point the ignition is synchronized. We assemble everything and install the transparent cap in the inspection window. We start and heat the engine, and rise to about 2000 rpm stable. Then we connect the stroboscopic gun clamp in the spark plug cable of the front cylinder (very important that this cylinder is).

Then we focus the strobe gun to the inspection hole. The gun will emit a flash of light at the same time that the spark plug spark occurs, and in the sale we should see the ignition advance mark (consult the manual to know how this brand is). If we do not see it we have to spoil the ignition adjustment screws and move it slightly until the brand appears centered on the window.

Conclusion
Once the brand appears in the window we already have our ignition "draft", that is, synchronized with the movement of the piston. From there the advance will automatically adjust based on the curves programmed in the ignition software. We ride everything again and we will try the motorcycle on the road, checking that it is soft, accelerates well and has power.

Frank Burguera

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