Rode 40 miles then it quit...

Battery terminals snug and proper

Pagala wrote: Suspect electrics.

Whenever I've had a similar problem, it's been after I'd had the tank off the bike and disconnected the battery, and hadn't tightened up the battery terminals.
The bike will run when the leads are touching the terminals, but when running it will bounce around and stop touching.

Make sure battery terminals and connections are tight.

I have a coil tester, I will try and ride enough to get them warm and test. Any idea what spark jump gap test should be close to when coils are healthy?

Zeerx wrote: Could be one of the coils. They heat up during running and short out internally. After coling off a while they’ll work and short again. Thats exactly what happened to my brothers KZ1000. Good luck.

The problem could be anything in the charging circuit. Someone earlier had a charging issue and it was a disconnected ground wire on his rectifier.

We'll check your stator output. You have a different design that I'll have to research a bit.

Meter on AC V
Engine running.
Idle
You have 3 yellow wires. Do not disconnect the connector. Just backprobe the wires. You want to check each combination at idle. You'll have 3 readings. It doesn't matter on probe polarity as it's AC voltage.
Note the voltage.

Raise rpm to 3000
Note the 3 voltages

Raise to 5000
Note 3 voltages

Turn off bike

rebreath wrote: Guys at z1 showed me via parts pic that 2 and 4 are open to the world. They do not have any vacuum pull . I left these open with lines curved down. 2 also has a vac nipple they said should be for petcock and yes it has an accelerator pump on the bottom of #2.

Mikaw wrote: Something is note adding up. The vacuum to petcock should be on #2. Can you post a pic of your carbs. Your bike should have VM24 with accelerator pump.

That is correct. But you said you were pulling off the vacuum line off #
1. Just wanted to make sure you had vacuum line on correct port. My mistake earlier saying vacuum was on three. I was thinking of a different group of carbs

That diagram is for the 1977 Kz650 only. It is a 3-phase system with an excited-field alternator. It uses a separate regulator and rectifier. The regulator controls the field-coil which is the thing attached to the green wire shown in the alternator (labeled "AC Generator")..

All Kz650's after 1977 used a permanent-magnet alternator and combination regulator/rectifier. From 1978 until 1980 or so they were 1-phase systems. After that, they were 3-phase (perm-mag, combo reg/rec). So after 1977 you will no longer see that field-coil in the schematic of the alternator.

1978 and 1979 Kz650's did not have a dedicated sense line (brown wire) on the reg/rec. At some point it was added in later models, maybe when it went to 3-phase, but it may have been earlier during the 1-phase years. (I haven't confirmed the sense line details with all Kz650 wiring diagrams yet.)

The original poster most likely has 1-phase, permanent-magnet, combo reg/rec. The bikes using that system, especially the 1978 and 1979 years, have been known to have charging issues when running a Dyna S ignition. That is why I asked him if he was running the stock ignition or not, but I don't see an answer to that question. The fact that there is no change in voltage, though, implies it's not charging at all so the ignition load is not likely the cause of the problem.

My apologies, I thought I responded to all posts. I AM running a dyna s ignition. Switched over many years ago when I lived in the keys. I was putting points in every couple weeks. It is a 1980 650 ltd

loudhvx wrote: That diagram is for the 1977 Kz650 only. It is a 3-phase system with an excited-field alternator. It uses a separate regulator and rectifier. The regulator controls the field-coil which is the thing attached to the green wire shown in the alternator (labeled "AC Generator")..

All Kz650's after 1977 used a permanent-magnet alternator and combination regulator/rectifier. From 1978 until 1980 or so they were 1-phase systems. After that, they were 3-phase (perm-mag, combo reg/rec). So after 1977 you will no longer see that field-coil in the schematic of the alternator.

1978 and 1979 Kz650's did not have a dedicated sense line (brown wire) on the reg/rec. At some point it was added in later models, maybe when it went to 3-phase, but it may have been earlier during the 1-phase years. (I haven't confirmed the sense line details with all Kz650 wiring diagrams yet.)

The original poster most likely has 1-phase, permanent-magnet, combo reg/rec. The bikes using that system, especially the 1978 and 1979 years, have been known to have charging issues when running a Dyna S ignition. That is why I asked him if he was running the stock ignition or not, but I don't see an answer to that question. The fact that there is no change in voltage, though, implies it's not charging at all so the ignition load is not likely the cause of the problem.

Mikaw wrote:

rebreath wrote: Guys at z1 showed me via parts pic that 2 and 4 are open to the world. They do not have any vacuum pull . I left these open with lines curved down. 2 also has a vac nipple they said should be for petcock and yes it has an accelerator pump on the bottom of #2.

Mikaw wrote: Something is note adding up. The vacuum to petcock should be on #2. Can you post a pic of your carbs. Your bike should have VM24 with accelerator pump.

That is correct. But you said you were pulling off the vacuum line off #
1. Just wanted to make sure you had vacuum line on correct port. My mistake earlier saying vacuum was on three. I was thinking of a different group of carbs

Sorry must have mis typed.There are two nipples on #2...one is the open vent and the other is vacuum. I am using that vacuum to petcock

Most 1-phase, perm-magnet Kz650's run fine with a Dyna S and charge fine as well. But some small percentage don't, and like I said it's usually 1978 and 1979 Kz650's more than any other models that have a slightly weaker charging system.

In your case, I don't think it's the Dyna S (assuming the Dyna S is working properly, and it sounds like it is). In your case, I think the reg/rec may have failed so a few tests are needed.

Can you confirm you have only two yellow wires in the charge system? Does your reg/rec have a brown wire? If not then the reg/rec should only have 4 wires, correct?

One test the manual will describe is running disconnecting the connector at the reg/rec and running the bike. It will then ask you to measure the AC voltage on the two yellow wires coming from the stator while holding a steady 4000 RPM.

Some manuals have the test results swapped between the 1-phase and 3-phase models.

The AC voltage on the two yellow wires from the stator should be close to or above 75 v AC. This is what you should see.

(The manual also describes a test for the 3-phase version measuring the AC voltage on one pair at a time of the 3 stator wires. The voltage for each pair should be about 50 v AC or higher. Some manuals have the 75v and 50v results swapped.)

There are 5 wires actually..1 brown,1 black,2 yellow and 1 white with red stripe. Three go to plug...2 yellow and the black. White w/red connects with same wire pattern and brown goes to another single connection. Tried to get pics

loudhvx wrote: Most 1-phase, perm-magnet Kz650's run fine with a Dyna S and charge fine as well. But some small percentage don't, and like I said it's usually 1978 and 1979 Kz650's more than any other models that have a slightly weaker charging system.

In your case, I don't think it's the Dyna S (assuming the Dyna S is working properly, and it sounds like it is). In your case, I think the reg/rec may have failed so a few tests are needed.

Can you confirm you have only two yellow wires in the charge system? Does your reg/rec have a brown wire? If not then the reg/rec should only have 4 wires, correct?

One test the manual will describe is running disconnecting the connector at the reg/rec and running the bike. It will then ask you to measure the AC voltage on the two yellow wires coming from the stator while holding a steady 4000 RPM.

Some manuals have the test results swapped between the 1-phase and 3-phase models.

The AC voltage on the two yellow wires from the stator should be close to or above 75 v AC. This is what you should see.

(The manual also describes a test for the 3-phase version measuring the AC voltage on one pair at a time of the 3 stator wires. The voltage for each pair should be about 50 v AC or higher. Some manuals have the 75v and 50v results swapped.)

Pics

Pics

Check for AC Voltage on the 2 yellow wires at idle and at 4000rpm.
Backprobe the connector and make sure the two probes don't touch each other.
Tell us what the voltage is.