Inductive Discharge or Capacitive Discharge?

Is the KZ 1000 Dyna - S and Coils ignition considered a Capacitive Discharge or is it a Inductive Discharge ignition.

I think its a Capacitive Discharge, but wanted to check.

Thanks

No capacitor in the Dyna S or any KZ factory ignition.
They are all what is called a flyback ignition, sometimes called "Kettering" after the guy who developed it for GM.

Kettering used points. The factory electronic ignition is a transistorized Kettering ignition, as is the Dyna S.

Both CDI and Kettering use induction to step up the voltage. Only Kettering uses the coil's inductance to store energy.

Many people called the KZ ignition CDI because Kawasaki used CDI on some of their two-strokes in the 1970's, so they assumed Kawasaki would use CDI on the KZ's. But they did not.

Kawasaki still uses CDI on some of their bikes, like the KLR650.

thanks for the history lesson, but my AFR manufacture only gave me the two choices Capacitive Discharge or Inductive Discharge.

www.daytona-sensors.com/download/Tach_Adapter_Instructions.pdf

I found this:

Inductive System:

The inductive, or Kettering system of ignition, soon replaced the magneto design in motorcycles. Inductive ignitions use a battery to store electrical energy for the combustion chamber's spark. Points and a condenser channel current to a primary coil. The coil pulses energy to a secondary coil with tightly wound, small-gauge wire. The voltage is increased from 12 volts to 20,000 volts or more to create a spark. Some newer motorcycles feature electronic timing controls instead of points. Multi-cylinder engines use distributors to send the spark to successive cylinders.

Capacitive Discharge Ignition:

The latest motorcycle electronic ignition systems are called capacitive discharge ignitions, or CDIs, and use energy-storing capacitors charged by high-voltage oscillator circuits. A spark is induced by a circuit discharging a capacitor into the primary coil. As in inductive systems, the current is amplified by the difference in secondary and primary coil windings. A 400-volt capacitor impulse can generate around 40,000 volts in the secondary coil. Some CDI systems initiate multiple sparks to increase spark duration.

After reading the two, I call it a Inductive System.

On the Electronic ignition of the 80's Kawasaki's, there's a unit called the IC Igniter, it actually gives the ignition coils their grounds, firing the coils & sparking the plugs. The trigger affect is done via the Pulsing Coils(behind a CD sized right engine cover).

That text has some info slightly off, but calling it an "inductive" system as opposed to a "CDI" would not be incorrect. It's just that the proper term, or more precise term would be flyback or Kettering.

I believe CDI is actually older than transistorized Kettering. It uses an SCR thyristor. So even though modern ignitions use it, really old ones use it too. Transistorized flyback ignitions showed up around the same time, or a little later, depending on the manufacturer.

That description for the "inductive system" is somewhat vague, and slightly misleading. They are incorrect that 12 volts is used to create 20,000 volts. In both the CDI and Kettering there is a 300 to 600 volt spike on the primary side of a coil. That is usually stepped up by a 100 to 1 ratio in the coil from primary to secondary. There are plenty of better descriptions of a Kettering points system on the internet if you are interested.

Also, they say the battery stores energy for the spark in an inductive system. But that would also be correct for a battery-powered CDI. And conversely, CDI and Kettering can both work without a battery.

What they should have done was made a distinction between the coil storing spark energy in a Kettering/flyback ignition versus the capacitor storing energy in a CDI.

Incidently, a magneto is sort of a mix of the two. It uses induction in a coil to store some energy, but then the discharge is routed to a step-up coil, much like a CDI does when it discharges.

MFolks wrote: On the Electronic ignition of the 80's Kawasaki's, there's a unit called the IC Igniter, it actually gives the ignition coils their grounds, firing the coils & sparking the plugs. The trigger affect is done via the Pulsing Coils(behind a CD sized right engine cover).

It was sometimes called a "transistor" ignition because a transistor switch replaced the points in the current path from the low voltage coil terminal to ground.

As for:

Capacitive Discharge or is it a Inductive Discharge ignition.

Any system that uses a coil with a switch in the negative lead (whether it is points or solid state switch) is an inductive discharge type. So, Kawi factory electronic ignitions are this type although the switch is transistor type.

The actual correct term for this type of design is a flyback converter, and the device often incorrectly called the "coil" is actually a flyback transformer that steps up the voltage by a large ratio of the transformer windings. Current flows in the primary winding when the points are closed, and when they open a large back EMF voltage is created and the energy stored in the core is dumped out the secondary winding across the spark plug gap.

Capacitive discharge is different because the capacitor dumps a pulse into the transformer to create the spark. A great advantage is the coil winding has no DC current flowing in it like the flyback design so the coil runs much cooler.

I called DYNA and asked what there DYNA-S system is considered, they said its an Inductive Discharge System.

Listening to electrical engineers argue reminds me why so many of us are single.

:woohoo:

Pretty good overview of ignition theory.

www.jetav8r.com/Vision/Ignition/CDI.html

This is the part that always makes me laugh:

Automotive COIL (also called an "INDUCTOR")

An iron core is wrapped with 2 long "coils" of wire. The "PRIMARY" winding on the outside and the longer "SECONDARY" winding on the inside.

An inductor with two windings is called a transformer.... an inductor has only one winding. But, it's still (incorrectly) called a coil and probably always will be.

Detailed analysis pretty well done.

www.worldphaco.net/uploads/CAPACITIVE_DI...CHARGE_IGNITION..pdf