To the electrically minded

WAY COOL!!! I know you went thru a lot of pain chasing it down, but in the end you fixed it!!

Glad to hear you got it fixed,,, somethings are just harder to track down than others.
Ride safe.

Cool! Good job!

No one get mad, but there is one small electrical issue.

So about twice in the last week, I've blown the 10amp fuse that has a brown wire output. This circuit feeds the high brake light, the neutral light, oil light, fuel light, and the tachometer. Each time it has blown, there hasn't been to be any noticiable trigger.

Instead a few minutes before the few blew, the tachometer needle would for a moment flicker up down and all over. The engine wasn't changing but the needle would shoot all around.

Today on my ride home, I noticed another interesting symptom. When in neutral, the neutral light was one. If I revved the engine from 1000 to 5000 quickly by snapping the throttle open, the engine would pop. Almost like a backfire, but only on the accerlation side. What was weird was the neutral light would flicker along with the pops in the engine.

Can anyone explain why a pop on rapid throttle opening in the engine would effect this subcircuit electrically?

My friend's KZ400 would do a similar thing occasionally. It was an intermittent short.

I would assume that your short kills the ignition for a second, but not enough to blow the fuse, then when the ignition resumes, you get the pop. The vibration from revving may cause the short to occur briefly.

There are other reasons why it may backfire,but that would be my first guess due to the blown fuse. The fuse may be a short in the front brake switch or wiring. If you can recreate the backfires, then disconnect one brown circuit at a time, until you can't re-create the back fires, that will tell you which circuit the short may be in.

If the short is in the actual ignition circuit, it will be a little harder to find.

Post edited by: loudhvx, at: 2007/06/28 23:39

Well, I haven't found a short, but I have found something odd about my bike. Apparently knocking is a problem.

With regular gas (87 octane), #3 doesn't fire at idle and I get a "helicopter" noise, that's kinda loud. With premium, the sounds is much much less, and #3 is firing at idle. Also, with premium, the popping above 4,000 rpm that was flickering the neutral light goes away.

Could the popping be due to detonation? I don't know that much about combustion theory, so I'm relying on others to tie the gas change to the electrical change.....

Detonation would be more noticeable during acceleration.

One possibility is crosstalk in the ignition module. That is pretty common. You need a timing light to check it. With the strobe on the advancer, the light should light up the 2-3 mark, but if the 1-4 light occasionally lights up, there is crosstalk. The crosstalk spark is weak, so it may not fire the cylinder with premium where it is more resistant to ignition.

If it is crosstalk, then see this mod I designed. It helps eliminate the crosstalk.
www.geocities.com/loudgpz/GPZgmHEImod.html

I know this is going to open up a can of worms, but are the carbs clean?
also you can use the timing light to watch for a miss, hook it up to the #3and go thru the rpm range it should have a steady spark, if not look at the plug wires first,

Definitely sure the carbs are clean. I had sent them to wiredgeorge for the complete overhaul in march before this season.

I'll checkout crosstalk/misfiring off of the #3 wire when I get some time later this week. Is there any particular way to see misfiring easily?

dnpurdy wrote:

...I'll checkout crosstalk/misfiring off of the #3 wire when I get some time later this week. Is there any particular way to see misfiring easily?

The timing strobe-light is the best way.

Ok, no crosstalk. No matter which spark wire, it flashes only when it should.

However, at idle, #3 misses a flash about every second or second-and-a-half, with an accompanying engine little noise. The other cylinders all flash consistently at idle.

As I rev the engine, on all spark wires, the light drops flashes. The dropping of the lights mostly matches the flicker on the neutral light.

No idea what this means.

Could be there is still a loose connection or short somewhere. The momentary loss of power may cause the light to not flash. I think an o-scope would be the only easy way to tell if the instantaneous voltage drops very low.

As far as #3, that could be a plug wire problem. Since the problem is not happening on #2, perhaps the lead to #3 has a weak spot. I'm not sure if you can swap the coils or wires, but that might tell you if the problem is on cylinder 3 or if the problem is a coil or plug wire.