KZ900 Ignition Diagnosis

Just acquired my '77 KZ900. See more on the history of the bike here in my intro thread .

Anyway, It has no spark. All other electrical works except the headlight. Bike has a Dyna III ignition system. The first time I cranked it over, I got some smoke that appeared to come from the DIII box. Subsequent cranks got no smoke. So I'm assuming the box is fried.

I've got 12v to the yellow/red wire to the coils, and power going into the DIII box. But the black & green wires from the box to the coils are only at .5-.75v whether the ignition is just on or it is cranking.

Can I just swap in a Dyna S ignition? Was anything I need for the DS to work removed when the DIII was installed? The DIII doesn't seem to be available for the Kaws anymore.


Click the below thumbnails for larger pics of everything. There are a lot of plugs & wires that aren't connected to anything, but none of that should have changed since the last time the bike actually ran, about 7 years ago. Any idea what some of these disconnected wires might be? Thanks for an help or insight!

Of course after posting this, I found the instructions for the DIII and DS on the dyna Web site. Looks like the DynaS would hook right up in its place.

Think I am safe in assuming it is the DIII that has failed?

Post edited by: moonwell, at: 2007/05/23 00:36

The readings you have are not bad. The green wire, and the black wire will have close to zero volts when the bike is sitting or running. To see the voltage fluctuate you need to turn the crank over very very slowly. The voltage on the black and green coil wires will only briefly go to 12v, that is only for a small portion of the crank rotation.

I believe the III should be more reliable than the S because some of the electronics are away from the engine on the III, but I don't know for sure.

The black-green-yellow wire connector may be for a brakelight failure device.

Post edited by: loudhvx, at: 2007/05/23 03:13

Before pitching the Dyna III, contact Dynatek and talk to their tech support folks. They probably have some way of determining if their box fried. The Dyna S is very inexpensive and simple to install, if you need to go in that direction. It is likely less expensive to pick one up from www.z1enterprises.com than from Dynatek directly. I guess you already have Dynatek's website if you found their instruction .pdf files.

if you will call them, they will let you send it in with a rma number, look it over, if its bad they offerd me a upgrade at a very good price, think it was about 60 bucks.
got to say they were very helpful

I did a few more test last night, including disconnecting the the sensor wires & grounding one of them, which according to dyna should result in the plug firing whenever it is grounded. I ohmed the coils & everything looks good there.

I'll be calling dyna today to see if they can do anything for me, otherwise I'll just pick up the dyna S from Z1.

I called up Dyna last week. They'll hook me up with the Dyna S for $69 after they test my old unit. Pretty sweet deal if you ask me, since I was looking into the S anyway

Shipped them the III last week. They should have that on Wed. Hopefully their turnaround is quick