82’ Kz 750e Charging system issues

Hey there, I don't have much experience with the bikes charging system, but I'll explain what I have and see anyone's input to solve this. My bikes voltage have been terrible, idle at 12.5 steady. So at least isn't draining the battery but not enough to charge it . Pass 4K I'll get to 12.9v, I tested the stator by the left side cover plug with the three yellow wires and  two other wires, I had .4ohms from each to another of the yellow stator wires. And nothing (infinite) from each of them to ground (I believe that it means stator is in good working order). The bike can't be started to check running voltage because started brushes were gone and needs replacement or repair. To be honest the book is confusing on how to test the rectifier unit, said something about 24v and a test bulb. Any pointers when I checked there was a wire that  connects to be starter solenoid and runs to the rectifier  (white and red) I believe . Book said to check resistance from there to each of the stator(yellow wires) and do 12 total checks. I checked swapping probes from the stator wires to the white/red and at any point I got anything. Any pointers on this? 

There's a couple voltage drop tests you can do.
Bike doesn't have to be running.

Key on/ignition on/engine not running
meter on DC V
reg/rec connector must be connected---you'll have to back probe the connector for the tests

Black probe on negative battery post(post is the metal part of the battery)
Red probe on yellow/black wire at reg/rec
voltage should be 0v.
If your voltage is higher than .5V then you have too much resistance on the ground side.
(if the reading is negative reverse the probes)

Black probe on positive battery post
Red probe on the red/white wire at the reg/rec
Voltage should be 0V
Higher than .5V --too much resistance on the positive side of the regulator.

Turn off the bike
Don't leave the bike on longer than 10min or the ignition coils will overheat. (it may be different because of your ignitor but it's a good habit for bikes around this time period)

wrote:

There's a couple voltage drop tests you can do.
Bike doesn't have to be running.

Key on/ignition on/engine not running
meter on DC V
reg/rec connector must be connected---you'll have to back probe the connector for the tests

Black probe on negative battery post(post is the metal part of the battery)
Red probe on yellow/black wire at reg/rec
voltage should be 0v.
If your voltage is higher than .5V then you have too much resistance on the ground side.
(if the reading is negative reverse the probes)

Black probe on positive battery post
Red probe on the red/white wire at the reg/rec
Voltage should be 0V
Higher than .5V --too much resistance on the positive side of the regulator.

Turn off the bike
Don't leave the bike on longer than 10min or the ignition coils will overheat. (it may be different because of your ignitor but it's a good habit for bikes around this time period)

thanks for sharing, I will make sure I never leave it on without running for that length of time or close to it. I'll check hopefully Tom this two test and hopefully I can confirm the regulator is fine. 

The factory manual has some tests that are useful to perform.  For example, disconnect the stator wires, run the bike at 5000 rpm, and use a volt meter set to AC and check for voltage between each combination of phases.  There should be something like 80 VAC in each of the three pairs of legs.

If this bike is a keeper than I'd go straight to a SH775 R/R.  These are an advanced SERIES type R/R which helps protect the stator from frying.  You can get a good used one off ebay for a fair price and they are super robust, so no worry about buying used.  I've got a spare if you are in need.  Be careful purchasing a SH775 because there are lots of fakes around.  Don't buy a new unit off ebay for example because they are almost all fakes.  Make sure the unit in question has "SH775..." printed on the top fin before purchase.

Nessism post=846164The factory manual has some tests that are useful to perform.  For example, disconnect the stator wires, run the bike at 5000 rpm, and use a volt meter set to AC and check for voltage between each combination of phases.  There should be something like 80 VAC in each of the three pairs of legs.

If this bike is a keeper than I'd go straight to a SH775 R/R.  These are an advanced SERIES type R/R which helps protect the stator from frying.  You can get a good used one off ebay for a fair price and they are super robust, so no worry about buying used.  I've got a spare if you are in need.  Be careful purchasing a SH775 because there are lots of fakes around.  Don't buy a new unit off ebay for example because they are almost all fakes.  Make sure the unit in question has "SH775..." printed on the top fin before purchase.

I searched for the rectifier and found a post you made about it, now I know exactly what it is and how beneficial it  could be. I had .56(something) from white/red to the rectifiers yellow wires. Checking it unplugged from stator and if I reversed the probes had nothing. Maybe my started because of how terribly it was, perhaps was shorting the system. If my rectifier is bad I will probably track and buy one of those sh775 (either way I'll do at some point)

Hey guys! This is weird but wanted to share. As I explained on my first post, my bike starter was dead, brushes were completely gone and pulverized, after replacing brushes and cleaning starter internals and stuff, tested it and then installed it. Bike starts every time now, even after being warmed up and the charging is now back to normal. So two things either somehow (I don’t honestly comprehend this theory but) the brushes were arcing and grounding and interrupting the charging or the 6pin plug wasn’t making a good connection and after testing snd plugging back it went back to normal. So now seems like I just have to rebuild the petcock and/or readjust floats. And should be ready. If anyone had any way of explaining if the starter had anything to do please help me understand the reasoning because I don’t and even tho is fix now I want to understand. once I fully assemble the bike and do a nice test ride  I’ll confirm operation. ( having issue with clutch finally got it to grab but need time to readjust because grinds when trying to put in first) I just need to add more tension to the cable. 

It could have been a loose connection.
Really hard to know. 
The starter shouldn't have much to do with it as power is cut off by the solenoid when you release the start button.
Good job!

wrote:

It could have been a loose connection.
Really hard to know. 
The starter shouldn't have much to do with it as power is cut off by the solenoid when you release the start button.
Good job!

thank you, that’s what I thought, because the white/red from the rectifier goes to the solenoid but on the part always hot and isolated, only when crank starting is when there is a direct path. I’ll remove the harness and use dialectic lube on it this weekend just to be safe.