ignition question

So the bike is running on 2 cyl and the ignition coil on 2/3 not getting spark. So i get a new coil. Still no spark. The voltage when the key is on but the bike not running to 1 and 4 is around 9 volts but only 2 to the 2/3 coils. So maybe that is why it is not firing? But what causes this? So I grounded the neg 2/3 coil to the bike and the voltage got better (still just key on not running). Not sure if I want to try starting the bike like this because i don't want to damage anything. Anyway, thought maybe some of the more experienced people might know. Thanks.

Your bikes aged wiring has caused a considerable drop in what should be at least 12 volts at the coils or what the battery voltage output is. The website www.wgcarbs.com shows how to install a relay bypassing the current dropping wiring in these older bikes and the parts needed.

Several guys here have done the modification with a great improvement in starting and running.

What needs to be done is go through the wiring harness looking for the green crud of corrosion as this will reduce the voltage/current to the various circuits(lights dim,turn signals operate slow etc.).

A selection of 400-600 grit sandpaper,some small jewelers type files,and a can of plastic compatable spray electrical contact cleaner(NOT WD-40 don't ask me how I know). This can take a while to do as the many and various switches and connections all need to be looked at and cleaned.

So I was thinking about getting the bike running and seeing if i could test the voltage of the red wires while plugged into the ignition coil. Both red wires with the neg on the multimeter to ground on the bike had over 13 volts so I'm thinking it isn't going to make any difference adding a bypass relay but what I'm curious about and haven't been able to find any info on is the neg wires going to the ignition coils, why is one green and the other black. I would think that both are grounds right? I think the problem might be with this green wire but not sure exactly what. What is the difference between the green and black wire and what exactly do they do? I was thinking of grounding the green wire but a buddy of mine said not to because it might have to do with the timing of the spark. Would the relay bypass fix this green wire problem?

Apparently we're talking about a 83 KZ550?

I'm not a 550 expert, but maybe I can help till Lou gets here (Loudhvx, resident electrical guru and 550 expert).

First off, when you ground the negative wire from the coil, the coil charges, when you break that ground the coil fires.

Next up, your bike was shipped with electronic ignition, and probably still has it, so those two negative wires go from the coils to the igniter.

Continuing, the reason the coils have separate negative wires is so they can fire at different times. Cylinders 1 and 4 are 180 degrees different than cylinders 2 and 3, so one coil fires 1 and 4, while the other coil fires 2 and 3. It's called a "Wasted spark" system, both plugs on a coil fire at the same time, but one of the plugs is on the exhaust stroke and is wasted.


Hope I haven't confused you more.

justinlitch wrote:

The voltage when the key is on but the bike not running to 1 and 4 is around 9 volts but only 2 to the 2/3 coils. So maybe that is why it is not firing?

Are you measuring the negative side or positive side of the coil? (The black meter lead should be on the battery ground, correct?)
If you are measuring the negative side of the coils (on the 2/3 coil, that would be the green wire), then the green wire is shorted, or the igniter is bad.


justinlitch wrote:

So I grounded the neg 2/3 coil to the bike and the voltage got better...

What exactly did you ground? No coil wire should be permanently grounded on your bike. And if you grounded it, what voltage "got better"?



Thanks Steell!