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It should only take about a second or two to get to 14v on the battery when revving, but that's if the battery is pretty well charged. The fact that you had a 6-volt reading on the battery is not a good sign for the battery. It may be on it's way out.

The next test is to eliminate the regulator portion (but still need the rectifier portion). If you disconnect the brown wire from the reg/rec, the regulator portion will be disabled. This means you will be getting full output from the alternator and rectifier. Make sure to watch the battery voltage carefully as you rev it up. Don't let it get above 15v.

If the voltage on the battery goes up quickly, then you need a new reg/rec.

If not, then it's the stator or the rectifier. To determine between those two is a little harder.

I tried it again today. The battery is fairly new about 6 months old. It was right at 12v when I started. The bike fired right up, only dropped to about 10V when I hit the starter. Let it run for a little bit, brought the rpms up to 4000 and held it there for awhile. It went up very slowly.

I then unhooked the brown wire like you said, stated it up revved to 4000 and held it. The highest it would go was 12.52V or so. As soon an I let off the throttle back to idle the voltage on the battery would just start dropping. The only load is the running lights and the headlight. It doesn't charge at all when idling.

Are you running the stock ignition?

Stock coils and dyna s ignition.

I suspected there may be a Dyna S involved. It seems whenever we get a thread about a 1-phase charging system just barely not able to keep up, there is also a Dyna S installed. And not only on Kawasaki's. I've seen it on Hondas as well.

A 3-phase stator often solves the problem, at least on the KZ650's that have had the problem. So you could try to get a 3-phase stator, (if it's a direct swap... we haven't confirmed that yet), or try to put the points back on and see if it charges ok with a stock ignition.

The Dyna S uses considerably more power than a stock ignition.

Lou, would there be a problem if the bike had a proper rewire done or would the charging system still not be up to the job?

I think the 1-phase stators used on permanent-magnet alternators just don't put out as much as the 3-phase ones. This seems true on the 550 and 650 KZ's. The 900/1000's don't seem to have this problem, or at least not as often.

The way the regulation works on those charging sytem puts stress on the regulator to burn off the extra power. With a 1-phase system you only have 2 SCR's to burn away the power, and in the early days of SCR's, they didn't handle as much power so I think the alternators had to be set to put out about as much as the bike would need. By going to a 3-phase system, you could use the same SCR's, but use 3 of them so you could then use a 3-phase stator which would give a little more extra power than what the bike needed.

When a Dyna S is used, you need more power. The 3-phase can deliver it, but the 1-phase has less extra power, so runs into a deficit if the stator or magnet-flywheel is marginal from age or heat.

A rewire won't really help in this case. Reducing the resistance of wires and switches will increase the current. This will allow the bike to use more power, and the alternator is already unable to keep up, so it may make the problem worse.

Well explained in simple terms for people like me! Thanks Lou

So is the dyna s pulling so much power that my voltage won't go up to 14v or so. I am sure it use to go higher. The only thing I have changed lately is getting the running lights working again. I still think the stator may not be working to its full potential!!

If I were to change to a 3 phase would the magnetic rotor have to be swapped also?
Along with the reg/rec and an extra yellow wire.

Running lights, by themselves don't make a large difference. But connecting them may just be enough to prevent the voltage from going higher.

There is also a possibility that the stator only puts out voltage when there is no load (which is how you tested it). Once it's under load, if there is a bad spot in the windings, there may be very little output from the stator.

You can try to do a load test on the stator, but it takes some work and most people don't usually want to do it.

You can try a 3-phase stator. Electromagnetically speaking, the rotor will work, but it's a matter of matching up the physical size of the stator so there is no interference damage. That's why I offered to measure my 3-phase stators earlier, to see if they match your 1-phase stator dimensions. As yet, I don't know of any confirmation that it's doable, so you would be breaking new ground.

Dimensions of the 1 phase stator are:
OD 103mm
ID 38mm
Hole spacing about 41mm/ 3 holes

How does that compare to the 3 phase?

Here's what I got for the 3-phase kz550 stator.

Mating surface is where stator hub mounts to cover.

Hub ID 37.4mm on non-mating surface.
Hub ID 38.0mm on mating surface.
Mating surface depth 7.4mm.

Overall OD 103mm.

Thickness at Hub 14.2mm to 14.4mm.
Thickness at OD edge 23mm.
thickness at windings ~25mm.

3 Mounting holes ID 6.6mm.
3 Mounting holes spacing 41.6mm.

So it looks like a 3-phase stator should just bolt in. Then you need the 3-phase reg/rec. as well.

We'll just have to keep our fingers crossed that it is not the flywheel magnets that are weak. Just to be sure... the flywheel doesn't wobble or have any scrape marks on it, does it? I have a few that wobble from crashes. I assume that will make for a weaker output.