TOPIC:

Here's another fun thought. Under the ignition-trigger mounting-plate, held in place by the metal brackets that support the triggers, are 3 magnets. If these are cracked the magnetic field they produce will be altered and the impulse affect on the triggers themselves will also be changed. The igniter is designed to detect a specific pulse from each trigger. If an adequate pulse (signal) is not being sent then it seems logical the igniter would not operate as designed.

Pg 236 Ignition System:The pick-up coil assembly (a magnetic impulse generator) resembles the standard contact breaker assembly in most respects except that the three sets of breaker points have been eliminated. In their places is an iron timing rotor and three magnetic pick-up coils. Each pick-up coil assembly consists of a pair of permanent magnets and a pick-up coil on a mounting plate. The timing rotor which is attached to the timing advancer has one projection. As the projection on the timing rotor passes through the magnetic field created by the permanent magnets on the mounting plate, a magnetic field alternately builds up and collapses. Each time the projection passes a pick-up coil core an electric current is developed. Each voltage pulse is conducted to the IC igniter where it is amplified and switches the Darlington power transistor on and off to control the primary current. The IC igniter utilizes the voltage pulse sent from the pick·up coil as follows to obtain stable induced high tension voltage from low to high engine speeds. The output voltage of the pick-up coil alternates as shown in Fig. K16. With rotation of the timing rotor the output voltage rises, and the power transistor conducts and permits IC Igniter primary current to flow when the pick-up coil output reaches the preset voltage. When the output voltage drops to the other preset voltage (V off) after passing the voltage peak, the power transistor no longer conducts, stopping the current flow in the ignition coil primary winding and inducing a high tension voltage that jumps across the spark plug electrodes. In the case of a standard breaker point ignition system the dwell time (the time during which current can flow in the primary circuit) decreases as the engine speed increases. This results in less current flow through the ignition coil primary winding and decreased induced voltage at high rpm. Conversely the dwell time in this transistorized ignition system is kept relatively constant by virtue of the pick-up coil output voltage. This is because the faster the engine runs, the higher the output voltage of the pick-up coil becomes and the sooner the V or voltage is reached. Therefore the dwell angle increases to keep the dwell time long enough at high engine rpm so that the induced high voltage does not decrease.

Illistration K26 page 241

According to this schematic reverse polarity on an ignition coil is possible so perhaps someone with a more formal background in electronics can step in and substantiate or invalidate any theory regarding this reversal having an affect on the igniter itself.

I'd just like to add one more thought now that we're talking about diagnosing electrical wiring on a 30 year old bike which has been through many hands.

I've run across this more times than I care to repeat. Seems many mechanic wanna be's have gone out and bought themselves a voltage tester either the ones that look like a screwdriver with a light in the handle and a lead on the back end with a clip to attach to ground OR a voltage meter with nice points on the ends of the leads, then they have the audacity to pierce the wiring with the nice pointy end of the lead and check for voltage. Here's the problem- a few years down the road and moisture has had an opportunity to get into the wiring through those holes left behind by the nice pointy leads and it corrodes the wiring which will increase the resistance to the point where it will burn through and then you have an open circuit. Prior to the burn through you have a loss of voltage and current which plays havoc on your systems. The only signs of an issue will be a tiny bulge in the wiring with green oxide around the tiny hole.

Hi Guys. Many thanks for all the info and keep it coming. Thinking out of the box is the point iv reached as going to be some thing so simple when found
As stated. Replacing the coils as new read 2.8 ohms with new HT leads. Original coils read 2 ohms. Shall be removing resistor.
Shall keep the forum updated re progress.
Been informed that coils produce a negative wave that can affect the IC Igniter unit, hence the diodes fitted to stop the feed back?

Have a read through Trikebuilder topic "Houston we have no Ignition"

www.kz1300.com/index.php/forum/electrica...-we-have-no-ignition

I believe that's the information you're referring to regarding the need for the ballast resistor.

Ager wrote: If it is the three main transistors i could find the code out from my mate he got them in NZ would have thought you could get them or i could send you some

Hi any chance of the codes for the transisters. Installed new coils and leads, so just need to sort out ign unit.

Regarding the "negative wave" that can damage the igniter unit, it is a reverse voltage pulse from the primary coil windings. When the coil magnetic field collapses, it produces a high voltage pulse from the secondary windings and also a reverse pulse (usually 200 - 500 volts) from the primary winding. Yes, the igniter has Zener diodes to shunt the reverse pulse to ground, preventing it from going into the Darlington driver transistors.

This was what scotch was referring to when he said that it looked like reversed polarity at the coil. He meant that someone might have reversed the primary input wires to the coil + plus and minus - terminals. That would reverse the polarity of the reverse pulse from the primary windings. Since the Zener diodes are polarity specific, they cannot shunt the reverse pulse and protect the transistors in such a case.