TOPIC:

Low DC output. Brand new battery.
1978 KZ650 with 1 phase AC.
RR is from Ricks and has been tested by them as good.
My Stator resistance is 0.8 ohms which is a tad out of spec. High by ~0.1 ohms.
Stator is not shorted to ground.
At 4-5k rpms I’m getting 40 VAC when the RR is disconnected. With RR connected I get 6 VAC.
DC output is 0.6 VDC.
Ground wire is perfect straight to battery and positive is perfect straight to battery. This is exactly how Ricks said to do it. This setup does NOT have an external “voltage sense” wire.

I’m assuming the Stator has gone bad since the RR has been tested by Ricks.

Any thoughts? I have the manuals and know how to use a DVM. I ALWAYS lick my fingers before testing hot wires.

If your stator shows 40 volts then it appears ok.

Some of the manuals are wrong. With a 1-phase stator, the AC voltage on the yellow wires at 4k RPM should be closer to 75vac.

It can be the stator or the rotor.

Are you using a Dyna S ignition?

I rode today and the battery maintained about 13 volts which is what Ricks Lithium RR specs at 13.4-13.5, so its still a little low.

I do get 70 VAC at 4k unloaded.

I do have a Dynatek DS-2 ignition. It uses 1 amp which is about 13 watts so the charging system handles it fine.

With ignition on, LED low beam and LED taillight on current usage is about 3 amps.

Could someone measure their VAC @ 4k rpms with loaded? As in leave the stator connected to RR and measure the VAC. I get a 6 VAC when loaded.

If you do a search over the last 15 years on Kzrider you will find the largest number of low-voltage complaints on Kz650's have to do with the 78 and 79 years of Kz650 when they use a Dyna S ignition.

For whatever reason the 78 and 79 1-phase charging system, with no brown wire on the reg/rec was made slightly on the weaker side. It would work fine with a stock electrical system. The Dyna S nearly doubles the dwell which nearly doubles the current draw on the system and this tips the scales so the marginal charging system can't quite keep up. Sometimes it will seem ok, but usually it's just a little lower than it should be to the point that the battery does not keep a full charge.

The solution is usually pretty simple. Install a 3-phase stator from a later Kz650 or Kz750-four. Then install a 3-phase reg/rec from a much more recent Kawasaki Ninja 250, 500 etc. They can be had used for $10 or $15 and they work fine.

If you have money to throw at it, you can install a high-output, aftermarket, 3-phase stator and then make sure to use a heavy duty reg/rec or a Shindengen Sh775. A high-output stator will rob extra crankshaft power if you use a shunting reg/rec, so the Sh775 would be a better choice in that case, but make sure it's a real one. There are plenty of counterfeits out there.

Most people report success with retrofitting used parts from later models, which is much less expensive.

This problem has come up so many times I have created a graphic and a video to address one possible reason why only some 78/79 Kz650's have this problem. It's not all of them either. It is just some percentage of those models. Some 78/79 Kz650's have no problem with a Dyna S and stock charging system, but when the problem comes up, 90% of the time it's a 78 or 79 650.

I have speculated that some 78 /79 Kz650 had one of the flywheel magnets flipped at the factory, but I haven't been able to look into it any further to rule it out. The factory originally used a design that could potentially end up with one magnet reversed. Then they changed the design to a type where the magnet would work the same no matter how it was installed.

Thank you for all that info. Really appreciate it. Most people have 35 watt headlight, and another 25-30 watts of running lights which would just about max out the single phase charging system.
The dyna requires 12 watts so in my situation I should be well within the capabilities of the charging system.

I rode for 2 hours yesterday with no issues so I must have magically fixed it. I’m not satisfied with my 13.0 volts but it works. The lithium RR has lower set point but I think it supposed to be at 13.9.

Anyone wanna check their loaded VAC?

I have money in this single phase system since I bought the Ricks lithium regulator so I’m interested in verifying my stator before I gut it all

I'm not sure how you are arriving at 13 watts for the ignition, but it si certainly higher than that.

Assuming you have the stock 4 ohm coils. and assuming you are getting at least 12v to the coils, the current draw on each coil is 3 amps. So that is 6amps total. Since the dwell is not actually 360 degrees, it may be a tiny bit lower than 6 amps. But even at 5 amps, the wattage draw is 60 watts.

If you are using 3 ohm coils, the wattage draw goes up significantly, possibly up around 80 watts if we assume 7 amps total.

If you are basing it off current measurement, it's possible you are losing voltage to the coil somewhere which would explain a low current useage on the ignition.

Since you are invested in the one-phase lithium regulator, then you might want to look into getting a new flywheel from a 750-four if you can find one cheap. It might have more powerful magnets. That would give you some more stator output.

Loaded VAC on the stator is normally very very low due to how meters estimate RMS voltage and the fact that the peaks are limited by the battery and regulator. This link probably has more than you want to know, but it does show why the loaded VAC reading is so low.

s3.amazonaws.com/gpzweb/GPZAltntrWaves/AlternatorWaveforms.html

Notice the loaded VAC can get down in the single digits (around 8v with lights off and 4000 RPM) and is actually lower at higher RPMs because the regulator starts to kick in. It's not as low as yours, but yours is a 1-phase system, and my measurements are on a 3-phase system, maybe that makes a difference.

I guess I botched that. I had amp meter connected I’ll go through this again this weekend. I must have some other issue

Since I have custom wiring on this kz650 I can run the fuse box through my dvm and I get 5.19 amps at idle and a little less than 5 amps at 7000 rpms.

So I need about 60 watts total. Headlight, twilight and ignition system. That’s through a pretty good Mastech dvm. I also have a nice fluke but I don’t wanna get it dirty it’s for use on lasers.

Next I reconnected the fuse box power.
Then put the dvm in the charge circuit. I’m only making 2.3-2.7 amps at 12.5 volts so obviously something’s weak. Maybe the magnets are tired?
Probably time to upgrade to 3 phase with the powered field coil

The older 650 system with the field coil is good, but it would be pricey to get it all together with a lithium regulator. The regulator works on a totally different principle than the permanent-magnet systems.

I think a 3-phase stator for your permanent magnet is all you really need.

Also, have you thought about just converting all the lighting to LED's? That might reduce the load enough that you don't have to change anything in the charging system. I think Steve posted about some LED headlight in another thread.

You may be right about the 3 phase. Either way I have to buy more stuff.

I have an LED taillight, headlight and turn signals. Eliminated the 4 amber running lights. My total current requirement with the bike running was right at 5 amps at about 12.9 volts.

Any idea if the kz550 magneto will fit the kz650? Im willing to buy one to test your hypothesis