Seven different types of ignition systems have been used on powersports engines. They can vary quite a bit, but it happens that two yardsticks offer the best way to compare these systems. The first is the ignition system's power source. The source is important because DC-powered ignitions behave one way and AC systems in another way—they even have different kinds of engine kill switches. The other very appropriate ignition system characteristic is whether the ignition fires its spark plug by rising its primary winding’s magnetic field or by collapsing it. Rising field systems are more powerful and tend to be more tolerant of spark plug deposits than are collapsing field ignitions, for example. Therefore, all the strengths and weakness, the pros and cons, of all the ignitions found as original equipment on powersports vehicles, which strengths and weaknesses ultimately reveal their real differences, are rooted in these two metrics. So they are useful in defining these systems.

Magneto ignition. Common on very early American and Brit bikes, magneto's main strength was its simplicity, while its greatest weaknesses was its legendary intolerance of dirt and its sensitivity to timing. Because it is AC-powered, the magneto ignition’s source voltage rythymically goes through a zero point, the midpoint in the AC sinewave. Due to either dirt or wear, the points open timing can happen closer to this zero spot than normal, and the result is vastly reduced voltage and even weak or no spark. In fact, points that are no dirtier than average and would therefore not phase another system just plain knock this one out. And its collapsing field characteristic—the fact that the system goes through two stages before it fires—just further impacts this ignition’s potential. It’s a delicate, somewhat below middle-grade ignition system, despite its endearingly vintage and even (in some circles) tough-guy persona. Though magneto virtually defined such machines as the British twins of the 50s and early 60s, today magneto ignition is found today solely on portable generators and lawn equipment.

Energy transfer ignition. Energy transfer is usually mistaken for magneto but though similar in some respects it is actually much further developed and better performing. Unlike magneto which is collapsing field, ET is a rising field system wherein the spark fires instantly on coil buildup, making it more effective where spark plug desposits are concerned. Visually distinguish energy transfer from magneto by counting the windings: two windings make it magneto, three typify energy transfer. Though a different system, energy transfer also has magneto’s sensitivity to timing and point cleanliness, which can keep the engine from even starting, though that’s not at all hard to fix. In just minutes I have brought kids’ ET ignition Honda Z50s back to life while anxious mothers stood gratefully by.

Capacitor discharge ignition. CDI is unique. It begins with a higher source voltage than any other ignition system, then stores this energy in a capacitor, whose triggered massive burst into the ignition coil makes for a blasting, rising-field effect. With such dramatic spark plug power, CDI easily overcame the snowmobiler's major problem, his two-stroke engine's spark-plug-trashing oil deposits. CDI is historic on that basis alone. CDI's one significant weakness however is a spark duration that is inherently one-third that of other ignitions, and this drawback in connection with lean-burn emissions-spec engines has resulted in it not being utilized on street-legal motorcycles as much as it otherwise might have been. Do not confuse, as many do, CDI with so-called “electronic ignition”. CDI is not simply another name for transistorized ignition, despite so much bad misinformation online.

Kettering ignition. Named after its inventor, a GM engineer, and often called "battery/point", Kettering is monumental in its history and longevity. Invented in 1908, its being battery-powered contributes to its classic drawback of being a power hog. As rpm increase, Kettering struggles to keep up and voltage to the ignition coil drops precariously low. Therefore, dirty wiring, connectors, switches, or a less than perfect battery can make Kettering perform below its best. Further, its collapsing field design makes it less compatible with spark plug deposits than it might otherwise be. However, due to its simplicity and ruggedness, virtually all four-stroke Japanese road bikes on the road today have Kettering ignition, either in its original points form or its later transistorized form.

Transistorized Kettering. Often called "electronic" ignition (and each of the Big Five has its own proprietary name), in transistorized Kettering the points were replaced with a transistor, which did the switching duty. Also a new part emerged, the electronic trigger, or pulser, which took over the points’ timing job. Other than this, there is absolutely no difference between first-generation transistorized Kettering and traditional Kettering. They differ only in the parts that do the switching and timing. This is also true of aftermarket Kettering systems such as the Dyna S and all of its contemporaries. Therefore, transistorized Kettering, just like standard Kettering, is a voltage-hog. And, advertising notwithstanding, transistorized Kettering—whether OEM or aftermaket—offers no gain in ignition performance over traditional Kettering.

Transistorized magneto. As electronics became more widespread, the magneto system lost its points, just as Kettering did. Tansistorized magneto is found mostly on stationary engines such as portable generators, lawn equipment, and a few very early model utility vehicles such as Kawasaki Mules (because they initially had stationary engines as powerplants). Transistorized magneto and traditional magneto differ only in the transistor and trigger replacing the points.

Transistorized energy transfer. Energy transfer also eventually got transistorized. You can now find transistorized energy transfer ignition on smaller-engined powersports products such as utility vehicles, scooters, and smaller offroad vehicles, ones that had standard energy transfer in earlier years. And, just as with the two Ketterings, other than the transistor and trigger, energy transfer and transistorized energy transfer are exactly the same system.

These then are the seven ignition systems used as original equipment. All are still to be found, and even the most advanced ignitions available today have one of these seven systems at their core.