78 KZ 650 charging issue.

Hello all, first time post.

Bought a 78 KZ650 with a title to use to smash together with my low mileage 77 engine I had rebuilt the top end on. Th,e 78 had been hot wired and the harness was a mess. Got it all together, fixed all the bad connections. Installed Dynatek ignition. Put in a new blade fuse box. Built the relay to put 12V to the coils. Use the stator and rotor from the 78 motor (2 phase, perm magnet).

Start it up and have 11.9V across the battery. Fresh battery, straight off the tender.

I've read these stators are just a bit weak, so I bought the electrosport stator and reg/rectifier. All installed, 12.2 V at idle.

Used the troubleshooting path from Electrosport. Found a 0.6 V gap on my ground circuit from reg/rec to neg terminal. Redid all my grounds with new wire, got that down to 0.12V. Charging around 12.5V at idle. Checked the positive side the same way and found 0.9V gap. So I stripped every old wire out and redid it all fresh. Got it down to 0.6V but still not charging enough. Started messing around and testing things at different spots. Looks like my headlight causes about 0.35V of loss. My dash lights about 0.15V. Running lights about 0.15V. And my EMGO keyswitch about 0.30V that varies if you wiggle the key around. I bypassed the keyswitch with a toggle and undid all lights and im at 0.09V.

How can I get this voltage bleed down? There is no old wire or connectors left except the last little bit on the signals and the turn relays. There a workaround here? Its getting ridding season and I want to ride the Kawasaki not the Honda or Harley.

Thanks all

No eBay APP ID and/or Cert ID defined in Kunena configurationNo eBay APP ID and/or Cert ID defined in Kunena configurationI too have a 78 kz650. the single phase AC is too weak. Everyone will tell you to swap it and I gave in and did it.

I got a kz650 CSR 3 phase stator and flywheel paired with Mosfet RR and im now stable at 14.0-14.1 volts from idle to redline. This is a safe charge for lead and lithium. I have lithium.

Last thing, I have a custom harness so I just snipped the harness for the stator and connected directly to the new RR then RR connects directly to battery.

I also have a 78 and have been thinking about changing to the 3 phase stator.
Do I need to buy the flywheel also? Or can I use my flywheel currently on the bike?

Thanks,

No eBay APP ID and/or Cert ID defined in Kunena configurationA SH775 is a vastly superior R/R compared to the FH020 (and similar) because it's a SERIES type unit. The FHXXX units are shunt type and will return unused current back to the stator leading to over heat stress. Series type R/R's shut off return current and helps protect your stator.

One problem with buying a SH775 is there are a lot of fakes on the market. This guy is selling the real deal parts for a good price though. Triumph sells a nice adapter harness that sells for $10 - PN T2500676.

From another post on the forum I saw someone had swapped the stock 2 phase system with a 3 phase stator and R/R made by electrosport.

I got those installed without issue, but it still seems like I am drawing too much current for it to keep up with if I use my stock headlight. The stator is supposedly making 30% more power than the stock 2 phase, but my problem persists.

Using Electrosport ESG010 Stator and ESR370 R/R.

I just don't understand how this new stator can't make enough power for a old halogen headlight. I know its not wiring related as I can put leads directly from light to battery while running and problem persists. Tried it on two halogen bulbs.

I am still using the stock magnet. I have two 650B magnet rotors, but they perform the same. Is it worth using another rotor?

I am using the stock magnet rotor on mine. Although I am trying to determine if that is my problem or not.

In the last 20 years, it has come up many times and is most often on 1-phase (2-wire is 1-phase, there is no 2-phase) Kz650's, which are from '78 and '79. When this issue comes up on '78 and '79 Kz650's, it's almost always (maybe always always) because of the Dyna S ignition. The Dyna S has a much longer dwell which dissipates a lot more energy in the coils.

The 78 and 79 Kz650 charge system seem to have been right near the limit of what the bike needed in stock form, but the Dyna S just puts it into the margins.

As Waktaylor mentioned, most people resolve it by upgrading to a 3-phase stator and 3-phase reg/rec. In upgrading the 1-phase stator to a 3-phase (3-wire) stator, you can theoretically use the original rotor. However, it's possible that the weak link is the rotor itself. and not just the stator being 1-phase.

I see the replacements from Electrosport are 3-phase.
Was the outside diameter of the replacement stator the same size as the old stator, in other words did it fit closely into the rotor?

Did the wire colors on the reg/rec match exactly (three yellow, one red or white, one black)?
I see a couple different ESR370 units with different color wires.
Did the new one have a brown wire? (It's possible that is a dummy wire.)

Thanks for the 1 phase correction.

I believe you are exactly right on the original system being marginal. Did a full test with that stock one phase system today, and on a fresh battery, warmed up motor. With no headlight and using the dyna ignition idle is at 12.8V, 12.2-12.3 with headlight. Tested two 78 650 rotors with same result.

Hooked up the Electrosport stator and R/R. 13.9-14.3V at idle, no headlight. 12.75-13V with headlight.

To answer your question, R/R has 3 yellow, one black, one white and one brown. The yellow are to the stator, black goes through ground, brown goes to a switched 12V, white goes to pos terminal. I will say I cant tell a difference between charging voltage or regulation with the brown wire disconnected.

Stator is same diameter as stock. Today I checked to make sure it wasn't off center or not fully seated. Looks good.

I have a LED headlight on the way and LED dash lights. I am hoping that will be enough power consumption reduction to get me rolling.

Just to be clear, most Kz's with permanent-magnet flywheels like yours, never really get much above about 13v at idle with lights on.

If you can get to 14v just off idle, or anywhere below 2000 RPM, with lights on, you are probably doing ok.

You can maybe install a temporary voltmeter to be safe. Then you can monitor the voltage while riding etc. There are some decent, small backlit voltmeters you might be able to mount to the bars.

The type of regulators we use with permanent-magnet alternators generally put out full power from the stator to the battery by default. Then the regulator senses the battery voltage and when it gets high enough, the regulator reduces output. There are two ways the regulator can sense the battery voltage. The 78/79 Kz650 regulator originally sensed the battery voltage through the output wire of the reg/rec. This means the sensing circuit is always attached to the battery. Another way that is probably more common, is to sense the battery voltage through a dedicated sense wire. That is the brown wire found on some/most Kz reg/recs. This allows for the sensing circuit to be disconnected from the battery when the bike is turned off which prevents the sensing circuit from draining the battery, though I don't think this has ever been a major problem. Another advantage is that this lets the regulator sense the voltage of the "system" rather than just the battery voltage. So if there are losses through various connections etc, this lets the regulator compensate by increasing the voltage a bit.

I think that some aftermarket reg/rec manufacturers may actually sense the battery voltage through the output wire, but they still include the brown wire for the appearance of compatibility to those systems using the brown sense wire. In that case the brown wire won't really do anything, but will still be there.

If the instruction emphasize the need for the brown wire to be connected to a switched 12v source, which is often a brown wire on Kz's, then you should do it.

As a test, you can briefly disconnect the brown wire at the regulator while a voltmeter is connected to the battery. Then give it a small rev. If the voltage goes to 15v, stop revving. The brown wire is probably needed. Do the same test with the brown wire connected and it really shouldn't go much above 14.5v no matter how much you rev. Either way, it's probably safer to leave the brown wire connected as instructed.

loudhvx, great information, thank you

Great info.

I have done something like this. If I disconnect the brown line, I notice 0 change in voltage. I don't know that I have done it and revved it to see how high it will go. I have tried running the brown wire straight to the battery positive to see if it changed it's charging behavior and it does not.

Today I may try that and I will also get some calipers out to measure the old and new stators dimensions to make sure the clearance to the perm magnet is the same.

All this in mind, do you think a more late-model permanent magnet for 3 phase would be a better current producer?

Thanks again all.

jacobbonta wrote: All this in mind, do you think a more late-model permanent magnet for 3 phase would be a better current producer
.

Bottom line I don't really know. This problem has been around for as long as Kzrider and usually once the stator was replaced with a 3-phase, the problem was diminished enough to not require any further action. Every now and then it wouldn't and I can't remember if there was a definitive solution or not. I suppose there is nothing else to replace but the rotor so if you can find a cheap one it may be worth a try. But again, your bike may already be ok now.

There are tests specified in the manuals but some of the manuals have errors regarding what the results of the tests should be.

When the stator is disconnected from the reg/rec it is said to be un-loaded. The manual says to measure the AC voltage between each yellow wire pair while the stator is disconnected while holding 4000 RPM. (Three possible pairs with 3-phase, and one pair with 1-phase.)

When you only have one pair, the AC voltage is higher than each of the three pairs on a 3-phase, as expected. Some Kz manuals incorrectly swapped the expected results between the 1-phase and 3-phase.

When you have a stock 1-phase stator with a stock rotor the expected AC voltage is about 75v AC at 4000 RPM. On a 1-phase 550 I measured 73v AC.

When you have a stock 3-phase stator with a stock rotor the expected AC voltage is about 50v AC at 4000 RPM. On a 3-phase 550 I measured 56v AC on each pair.

I'm not sure what the results would be for an aftermarket stator or rotor.