TOPIC:

Last year I had an issue with my battery dying on me. Seems it never had enough charge to run the electric starter, Kick start would always work. I checked for a drain with the key off and couldn't find a problem. Figured it was a bad battery, so I just made sure to keep it on a charger. This spring I replaced the battery with a new AGM type. Still have the same problem,

Bike is a 1980 KZ650. This is a single phase solid state Rectifier/Regulator system.

I started digging into the charging circuit. With a fully charged new battery it shows 12.7 volts with the key off, With the key on it drops to 11.5V. With the bike running at 4000rpm it just about recovers to 12.7 volts, so its not charging, well its not charging enough...

I checked the stator leads at the regulator, its making about 65 volts AC at 4000rpm. Is this too low? I checked for voltage at the red/white wire and the brown wire with the key on - looked fine there. Ground wire was good too.

I checked the rectifier, I unplugged and took it off the bike. I did a diode test on each AC leg (the yellow wires) between the (+) rail and (-) ground, they checked out.

I then followed the procedure in the manual to check the regulator. Instead of a 24 volt battery I used an adjustable bench power supply. I started at 12V and turned it up slowly, at about 14.8 volts the test light came on(between the AC leg and ground using a small 12v battery), so the regulator is working.

The connector on the regulator looks a bit crusty so I took the contacts out and cleaned everything up, I hooked everything back up with the same results, not charging enough. I tried a different regulator/rectifier just to be sure, same result.

So I think my Stator is just weak, before a drop the $$ to try a new one, does anybody have any suggestions? Hate to spend money on parts and not fix the problem.

According to the Kawasaki Service Manual the charging voltage should be "about 14.5v" at 4,000 rpm.

Below is a cut and paste from the manual on how to test the output of the alternator. Ed

Single phase? You have one wire from your stator? Odd.
The ones I have seen have 3 wires and they are 120 degrees apart, making them 3 phase.
If you truly have a separate regulator and rectifier, I would replace it with a modern R/R unit.
Polaris sells a SH-775 unit for around $70 that is a series R/R, which is far superior to the original shunt R/R units on most bikes.

Nope singe phase, 2 legs, 2 yellow wires. As opposed to 3 phase as the newer stators often are with three or more wires. Its a single solid state RR unit, but I checked the function of each part of it.

Tyler wrote: Nope singe phase, 2 legs, 2 yellow wires. As opposed to 3 phase as the newer stators often are with three or more wires. Its a single solid state RR unit, but I checked the function of each part of it.

Yup. That's the alternator the test cut and paste I provided is for. Two yellow wires from the alternator. Ed

Yup, yup, I have followed that procedure from the manual, it makes about 65 volts RMS. at 4000 rpm. Is that "A much lower reading" as the manual states?

Do you have a Dyna S ignition by chance?

Also there is about 0.4Ohm through the stator, and no detectable short to ground.

loudhvx wrote: Do you have a Dyna S ignition by chance?

Yes, As a matter of fact I do...

The Dyna S uses a lot more power than the stock ignition. This problem comes up on some single-phase, KZ650's. It's not a defect, but a bad match of aftermarket system with a charging system designed with little extra margin for power.

Most of the time, simply swapping to a 3-phase stator and reg/rec from a later year 650 or 750-4 will solve the problem. Another option would be to convert to a Kawasaki electronic ignition which is much more power-efficient, but you'll likely want the 3-phase system in case you ever want to add any other accessories.

If you do a search, you'll probably find several threads on this exact problem.

The Dyna S also causes similar problems on other makes as I have diagnosed this on Hondas, and possibly Suzuki's as well. On KZ's, it only seems to affect some of the single-phase 650's.

I learn something every day. I agree that moving to a modern charging system would be the best thing to do.

loudhvx wrote: The Dyna S uses a lot more power than the stock ignition. This problem comes up on some single-phase, KZ650's. It's not a defect, but a bad match of aftermarket system with a charging system designed with little extra margin for power.

Most of the time, simply swapping to a 3-phase stator and reg/rec from a later year 650 or 750-4 will solve the problem. Another option would be to convert to a Kawasaki electronic ignition which is much more power-efficient, but you'll likely want the 3-phase system in case you ever want to add any other accessories.

If you do a search, you'll probably find several threads on this exact problem.

The Dyna S also causes similar problems on other makes as I have diagnosed this on Hondas, and possibly Suzuki's as well. On KZ's, it only seems to affect the single-phase 650's.

Ok, that seems to fit with what I am observing, I can't find a clear fault in anything, just that its not producing enough voltage. Thanks you saved me a serious headache...

Ok so I need a stator and R/R Unit from a 650 CSR or a 750 and the wiring from the stator cover to the R/R unit.

Any other bikes Kawi or other wise that would have a stator that fits?