77 KZ1000A1 Voltage Regulator

My bike has me questioning the charging system. I put a new Yuasa AGM battery in last year. I notice it slowly uses up its charge resulting in slow turnover when starting. I just did a 130 km ride yesterday and it was quite sluggish turning over today. I put it on the maintenance charger then after a couple of hours, tested the voltage. 12.6 volts static, then 17.8 volts with it running around 4,000 rpm. I also noticed that my headlight has just burned out on both filaments. I had a second light that I removed last year because it was very erratic with brightness all over the place. Both are Philips H6024 lights, but from new, one was steady while the other is all over the place. The steady one is now dead. 

If I check my manual, I see the voltage regulator exactly as mine looks:
 

If I check Partzilla, it shows the voltage regulator as a very different looking part, part #28:
 

First, the regulator is likely the culprit here isn't it? Next, why does the Partzilla part look so different from the one on my bike and in the manual? To make matters worse, searching the Partzilla part number 21066-026 shows 2 types, the wire type like in the diagram and a very different looking beast:
 
If the voltage regulator is the problem, what should I replace it with and does anyone know the part number of the OEM one in my manual? I did undo the connections to mine and they looked sparkling clean.
Thanks.

Z1's had a voltage regulator and a rectifier.  The voltage regulator looked like the one in your manual photo.  I think in 76 they went to a combination unit similar to the one in your ebay photo.  What does the regulator look like on your bike?

Your regulator may indeed need replacing.  But you should also check the alternator for voltage.  It's a 3 phase alternator with three yellow wires.  Call them A, B and C  Disconnect it at your electrical panel and check voltage from A to B, B to C, and A to C.  They should be producing around 50 volts at 4000 rpm.  If all is good then you can be more confident the problem is the regulator.

At 17.8 volts you probably have boiled all the electrolyte out of your battery.
AGMs have the disadvantage of being sealed. You can't add water.
If you had a dry lead acid, at least you could keep your water levels up.
17.8V would still damage the lead acid battery, but not due to low electrolyte.

Your regulator should be keeping the voltage below 15V at 4000rpm.
I'm not sure if you can adjust your regulator. There is a possibility you can.

Your regulator is
21066-025 not 21066-026
I think 21066-026 may be a diode(it was discussed on this site in 2013)
www.kzrider.com/forum/4-electrical/59107...s-this-p-n-21066-026

www.partzilla.com/catalog/kawasaki/motor...r-rectifier-77-78-a1




photo:partzilla.com
 

wrote:

Z1's had a voltage regulator and a rectifier.  The voltage regulator looked like the one in your manual photo.  I think in 76 they went to a combination unit similar to the one in your ebay photo.  What does the regulator look like on your bike?


The one on the bike is the same as the one in the manual.
 

I have a couple of spares for my Z1.  Later this morning I'll dig them out and photograph them.

The photo F64 attached shows a rectifier in the lower right corner.  Do you have one on your bike?  It would attach directly to your electrical panel.

Regarding the part numbers & diagrams, there are two things going on.  First, the 77 & 78 KZ1000A diagrams are combined, so two different voltage regulators are shown in the drawing:  one for the 77 & the combo unit for the 78.  Secondly, there's a part number error for #27 which is a reg/rec combo unit, not a rectifier.  #27 is 21066-1008 & was used on the 78 model which has a different alternator rotor & stator.  I don't know if the combo unit can be used on the 77.  I'd guess yes, but that's just a guess without looking at a wiring diagram n stuff.
1978 KZ1000-A2 IGNITION/GENERATOR/REGULATOR  
www.partzilla.com/catalog/kawasaki/motor...r-regulator-79-80-a3

ps:  in the diagram F64 provided, in addition to the voltage regulator, your motorcycle also has the rectifier #27-1.   The reg-rec combo unit replaces those two parts.  That EB part appears to be a reg-rec, so it also replaces the rectifier, not just the voltage regulator.

Item 28 is a diode. I’m not good with electric stuff but it is in series with the hazards four way blinker. I have it on my ‘76 900’s and on my ‘78 1000B2

man 17v is way high should be more in the 14v range. Time for a Nessism SH 775 upgrade.

 

I checked and indeed, I have two.....haven't tested them so don't know for sure if they are good.  But they are for a Z1, which has a different part number.  I suspect the difference is because yours is located in a different location, requiring longer leads.  You're welcome to try one if you're desperate.

Thanks HRM, but you're right, the leads are much longer on the one on mine. I have the 2 part system:
Left side
 

Right side
 

When I get a chance in the next couple of days I'll pull the regulator and do the out of circuit test described in the manual:

 

Your number 28 show be here at red arrow. 

 

I removed the regulator today and ran the out of circuit test. + to Black Lead, - to Brown Lead gave 1340 ohms, + to Brown Lead, - to Black Lead also gave 1340 ohms, rather than the 300 ohms called for. The other combinations of leads all showed 0 ohms, so I suppose I need a new regulator. I haven't been able to source a used one yet, but seeing as the NOS ones I've found range from USD$250 to $475 plus shipping, I'll keep an eye out for a used one to show up on eBay. I'd really rather go the OEM route rather than getting an aftermarket combo unit, if possible.

If you don't care about keeping the bike original you can get a state of the art SH775 combination R/R for about $60 + $10 for a harness.  Vastly superior to the original separate regulator and rectifier and much cheaper.