TOPIC:

okay all, I need a hand. I have a 1980 kz750ltd that has never ever charged the battery. Here's a list of things I have fixed/replaced in my quest:

I have a dyna-s ignition with dyna coils on it
I have rewired the bike using weatherpak connectors
new regulator rectifier
new stator
new rotor
new plug wires

In addition to this, I have checked as many switches as I can find on the bike.

So, you are going to say, what can I think of that this guy hasn't? I don't know, but here's a strange happening on this bike:

If I unplug the headlight and start her up, she charges with 14.5V like there is no tomorrow. Works great. Now, plug the headlight in and....

11.9V at idle, 12.4V above 3000RPM.

So, I replaced the headlight bulb and still the same problem. Anybody ever seen anything like this before? any help would be greatly appreciated. Thanks

Jason

So maybe it's a problem in your headlight circuit? Bad ground?

kzrider.com/component/option,com_docman/...d/gid,195/Itemid,49/

could be a bad ground. I am going to try taking my hi/lo switch out of the circuit to see if that helps

So, I have owned my 1981 KZ750LTDH for 10 years. From day one it has never charged efficiently. I have spent the last decade trying to figure it out, and I have finally done it! Here's a run down of what I did in an ATTEMPT to correct the problem

replaced ignition switch
changed reg/rectifier 3 times
changed alternator windings
changed rotor
re-wired entire bike using weatherpak plugs - removed any unecessary electronics
replaced ignition module with dyna-s unit
replaced ignition coils with dyna coils
tested every blankity blanking switch and light bulb socket

After doing all of this, my charge issue still remained. My last ditch attempt was to modify the wiring to allow the bike to only run and charge. This allowed the bike to charge at the correct voltage!

I then began plugging in components one at a time. Hooked up the tail light: still charging. Hooked up the front/rear brake switches: still charging. Hooked up the speedometer: still charging. Hooked up the tach: still charging. Hooked up the turn signals: still charging.

Only one thing left, the headlight. Hooked up the headlight: NOT CHARGING!

Did the simple thing first, replaced the bulb even though the old one looked good. Not charging. Took the hi/lo switch apart and cleaned contacts. Not charging.

I finally took the light bulb out of the headlight and hooked it directly to the battery. Started the bike and... VOILA! Success in charging.

I disconnected the hi/lo switch from the wiring harness and wired the hi/lo contact of the light bulb directly to the harness and... NOT CHARGING!

I drank a beer and pondered for a while. I removed the headlight and calmly disconnected the lead for the lo beam, started the bike and.... IT CHARGES!

It turns out that the root of my problems for the last decade, the reason that I replaced all of those components, is because the damn hi/lo switch was turning on both the hi and lo element of the headlight! Who would have thought such a thing as a bad headlight switch would mess up your charging circuit!?

Now I can enjoy my bike right after I rejet to compensate for those dyna ignitions. That should only take a couple of months, right?....

Jason

jason8887 wrote:

It turns out that the root of my problems for the last decade, the reason that I replaced all of those components, is because the damn hi/lo switch was turning on both the hi and lo element of the headlight! Who would have thought such a thing as a bad headlight switch would mess up your charging circuit!?
Jason

Jason,
When I look at the wiring diagram for your bike that is in the Filebase, it looks like the low beam IS connected to the HI Beam. Notice the thin black line from HI trerminal to the LO terminal, inside the switch housing?

Post edited by: OKC_Kent, at: 2007/10/04 15:00

Kent
I thought that initially too, for the very same reason. That's why when I rewired the bike, I hooked the low and high beam up to the same hot wire.

However, if you read the section in the manual dealing with the reserve lighting device, it explains that the device automatically switched the headlight from lo to hi (or vice-versa) if one of the elements burns out.

I believe the diagram (and switch) are set up to work with the lighting device, and that under normal conditions, the device keeps both elements from being lit. I have no idea how this works, but it seems like a waste of technology to me!

Maybe I'm out in far left field on this? Anybody got a thought?

Well.......I wonder if the reserve lighting device is bad? Maybe if it was it would cause those problems?

Does the manual show any way to test it?

I don't remember if there is a test or not. I tried to solve the problem by replacing it with a spare at first, but it did not fix the problem. I then removed it all together, and still had the problem. The only thing that seems to have helped is to remove the hi/lo switch completely, and only run the light on 1 element. I am at a loss for why this makes a really significant difference, but it does. I'm just happy my battery won't go dead on me any more!

what your explaining could be caused by a slight ground between the reserve lighting device and switch "tricking" the reserve lighting device into thinking one of the elements is not lighting.. most probably caused by the wires being pinched somewhere.. when this happens it will rob voltage from the generator used by the charging system by displacement through the frame.. of course the voltage is so widely spread and so weak it will be undetectable so you will have to search very carefully.. one way to make sure is to bypass the wiring to the switch using wire straps straight to the reserve lighting device and from the battery to the reserve lighting device do the same while the original ciruit is disconnected.. if both Hi and Lo elements light then most likey it is a bad switch if not then permanently bypass the original wiring so you can use both Hi and Lo beams.. or just keep it the way you have it

Post edited by: kz650csr81, at: 2007/10/05 17:40

Post edited by: kz650csr81, at: 2007/10/05 17:42

Post edited by: kz650csr81, at: 2007/10/05 17:46