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Discussion Starter #1
I'm helping an old guy from my work get his bike going again it's been stuck in the back of his place for the last twenty odd years after he rode it over from the coast. Lucky we are in the desert in the middle of Australia nothing rusts here its just too hot and dry. The wiring all looks pretty okay the carbs are going to need some work in fact the whole things going to need a lot of work but I've got to start somewhere... I've tried tracing some of the wires back and it seems like there's power getting to the indicators and the horn the ignition coils etc but nothing turns on no lights on the dash nothing. I'm pretty sure it's been messed with and there's stuff missing from around the fuse board. Id appreciate any advice guys. Thanks in advance.
 

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Well you certainly have your work cut out for you. I just finished rebuilding the wiring harness for my 1984 Kawi ZN1100 Shaft drive LTD. A lot of the electrics look the same or very similar as your bike. So take note your bike may be like mine in that it includes a "Reserve Lighting Unit". This means the headlight will not turn on until the bikes sees charging voltage coming from the alternator. So don't waste any time on the headlight circuit until the bike runs. The idiot lights on the dash should come on with the key.

Do you have a wiring diagram or better yet, a service manual? Also it looks like you will need to replace some connectors and terminals. I can recommend Motorcycle Connectors
They have all the old Kawi connectors and advice on crimping tools and very reasonable prices. (no affiliation)

The unused connectors might be for accessories so I would not worry about those. In general, on an old bike like this, the connectors will be your biggest problem. Each connector should be carefully examined and cleaned or replaced. Look for brittleness of wire insulation and signs of overheat which typically comes from too much resistance from a corroded connection. Those wires should be replaced or they will give you trouble down the road.
 

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Pics of the connectors are only partially helpful. You'll need to note the wire colors & how many wires are going to each connector. The meter socket assy connectors are inside the headlight bucket.

Wiring diagrams. mbsween. bike-night. KZ750L3. Scroll down & click "The Bible" link.
the site has wiring diagrams & the cruddy 750-4 pdf manual that's a poorly copied version.
wiring note: not a problem here, but some of the wiring diagrams are mislabeled in the links: the 1981 Ltd is an H2, the 82 is an H3, & the 83 is an H4.
Kawasaki Service Manual: 750turbo.com >> Full manual (128mb PDF).
1980-85 750-4 chain drive manual. Yellow/gold cover w color wiring diagrams.
1980-84 KZ750-4 & KZ700. 1983-85 ZX750.
manual note: there's a cruddy black-n-white pdf floating around the internet, so be sure to get the good version.
 

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Discussion Starter #5
Thanks for the speedy and detailed replies gents. Very much appreciated. Ill take you up on your advice and will come back to you when I've made some progress.
 

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I would clean up, connect & identify as much as possible, then what remains should be more easy to figure out. There are various different connectors & how they should be connected is kind of logical. The junction box cover should have an informational label on it. Partzilla has diagrams w cross-reference. EB pics are handy.
 

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Discussion Starter #7
Had some time this morning. Got the wiring diagram started doing some tracing. So far with my diagnostic skills or lack thereof I have been able to blow the 30amp main fuse pictured twice. I did this by cleaning up the red and white wire where it comes out of the connector into the back of the fuse box it was quite corroded. Any suggestions would be welcome on what may be causing this or places to check. I'm stumped by the four pin connector which doesn't seem to have a home (pictured) and the top left corner connector on the front of the fuse box. Unfortunately no front cover to the fuse box. No power to any of the front connector leads to the key ignition, dash display or left and right handlebar switches. Found the connectors in the headlight bucket all looked okay but no power.
 

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Ok, now you are having fun! I trust you have figured out that it is best to do your connector cleaning with the battery disconnected.

The white plastic plug in the top left corner of your fuse box aka "the junction box" is an accessory outlet.

Do not be alarmed if some connectors appear to have missing wires because some of them never used all available terminals within the plug.

The homeless 4 pin white connector is probably for the connection between the igniter and the pickup coils, although without seeing the colour of the wires and the exact location, it is hard to tell.
This connector would attach to the battery box on the right hand side. Look for a mating connector that heads straight down and towards the bottom of the engine. When disconnected, the wire and mating plug can fall down out of sight.

A word of caution. The manual warns you not to disconnect any plug while the ignition switch is on or when the engine is running. This precaution is to protect the igniter and for my 84 these are no longer available. Of course this makes trouble shooting a lot harder. But you can certainly check for continuity with the power off and with power on using a thin probe you can test for voltage at the connector without pulling the connector apart.

Also, you may want to try a product called Deoxit to help with connector cleaning.

Cheers. Keep us posted.
 

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Discussion Starter #9
Thanks WFO KZ. I'm having fun but as you point out pretty nervous about doing some kind of irreparable damage 😳

I discovered a horrible three way solder in a lead running to the rear tail lights replaced that and then through a process of trial and error disconnected the lead to the alternator? and now have power to the light circuits dash handlebars etc. All the switches appear to work, high/low beam indicators both sides, neutral light also. The owners dog chewed the front left indicator off that's going to need some extra attention. The lead to the alternator looks to have been repaired by the same hand responsible for the terrible three way soldering job. Two of the wires run to just behind the battery box into what looks like a resin block? Assuming ground of some kind.

I'm pretty sure that set of wires is responsible for popping the fuse. Going back into the wiring loom behind the two cable connector the wires look factory but no idea where they go. There's a join in the wires running to the alternator which look very old, braided wires heat resistant possibly.

Any ideas also on where the two leads colour black/yellow and red/yellow coming out of the starter solenoid go?

Any advice on next steps? I've done my best to take pictures of the leads responsible.
 

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Excellent progress. I would test the alternator to make sure it is ok. Disconnecting the alternator should not suddenly make your lights work so please check that out. On older bikes it is not uncommon to see melted alternator wires and melted connectors where the alternator connects to the voltage regulator. This happens due to excessive resistance from corrosion which heats up the wires. I had to replace all of my alternator wires and install new connectors.

I have no idea what the resin block is. My bike does not have anything that looks like that. If you search your bike on Partzilla.com look through the parts diagrams and it will identify what it is.

My bike does not use the exact same colour wires on the starter solenoid. On mine, the Black/Yellow is common to battery negative so from the solenoid it travels to the junction box with many stops along the way since it feeds power to far more than just the solenoid. The other wire, which on my bike is Black/Red (probably corresponds to your Red/Yellow goes directly to the junction box. When you hit the starter button the junction box will receive this signal (assuming all safety switches are clear) and then the junction box passes the power to the solenoid. If you are not getting power to this wire when the starter button is pressed, start testing all the safety interlocks like side stand, clutch lever and neutral.
 

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Discussion Starter #11
Thanks again for the encouragement and advice.

I've been away for work this week but dropped the alternator off too be checked out on Monday. Apparently its no good. I hooked it up to a drill and spun it up whilst checking the voltage output and it did register .5 volts when the drill was maxed out. I would rather not fork out for a new one any ideas how to repair it? Any suggestions on where to get an alternator if necessary?

Also I can't seem to find a regulator/rectifier anywhere on the bike😫

The starter motor doesn't have power going to it when the ignition is on. The ignition coils have power going to them any ideas on how to test if they are bad?

Did you have to take the airbox out to remove the starter motor?

The green manual light is showing on the dash after I serviced the hydraulic clutch cable. The kickstand switch is good. Any other interlocks I should check for?

I'm keen to explore whether this thing is going to run before sinking too much money into it.

Next steps appear to be repair/obtain alternator, Re-check the wiring. Source a regulator/rectifier. This is probably a stupid question but should the bike turn over without the alternator and rectifier?

Thanks in advance.
 

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It sounds like you are trying to do this without a manual and I strongly encourage you to obtain a Kawasaki service manual or at least a Clymer manual that covers this model. Sometimes local libraries will have Clymer manuals.
The Kawasaki manual outlines a very simple, static alternator test that you can do without removing the alternator and without the bike running which would have saved you the time of removal and testing by others.

I would first confirm that the alternator is bad by doing the tests outlined in the Kawasaki manual, but the bike should run with a bad alternator as long as the battery is fully charged, but note, it won't stay charged for long. If the alternator is bad, then I would suggest buying an OEM or third party replacement. Rewinding an alternator is not an easy task. Get the part number from Partzilla, see if they have one and check on Ebay. Same thing for the regulator if you need one. I found one on Ebay for about $30.

You will likely find the regulator underneath the gas tank, above the carbs, nestled out of sight between the upper frame rails.

No point testing the coils if you are not getting power to the starter motor. One thing at a time. If you study the wiring diagram you will see where all the safety interlocks are. On my bike it was the clutch interlock that was at fault. After cleaning the contacts, the starter motor worked. The clutch interlock is located as part of the clutch lever and can be taken apart and cleaned.

And make sure you don't fall into the trap of confirming correct operation of the side stand interlock, and then leaving the bike on the side stand while attempting to test the starter motor. It happens. Sometimes we cannot see the forest for all the trees in the way.
 

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The 750Turbo site has a good manual. 80-85 750-4 chain drive models. Yellow-Gold cover w color wiring diagrams. There's a poorly scanned B-&-W version of the manual floating around the internet, so be sure to get the good version which may also be posted at KZRider.
 

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Discussion Starter #14
Thanks gents, I've had a really good look through the bike. Read over the manuals and traced the wiring diagrams. This bike has a lot of wires, it's water cooled and to make matters worse someone has gone in previously and removed the kickstand switch completely and has also disabled the clutch switch. I can't seem to find how they have done that, I'm confident that's the problem. It's been sitting in the desert air for the last 20 years.

It's pretty complicated and has a lot going on. The ignition computer thing gets really hot when I try and start it and the starter fuse stays cold. I'm starting to think I'm a little over my head. I live in a place called Tennant Creek absolutely smack bang in the middle of Australia. Not alot of bike shops around. Nearest one was 500km away before it closed down. The local auto electrician wasn't particularly helpful doesn't do bikes.

When I jump the solenoid the starter motor spins but apparently these bikes have stater clutch. Nothing else happens. The stater clutch seems pretty involved and I'm not about to start spending up on an alternator regulator solenoid, stater coil etc if that's the case.

It's a shame because the rest of the bike might be okay. Oil in it looks good, all the switch gear works.

He's a good mate, but think this is it unfortunately 😩 thanks for all your replies.
 

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Sometimes the kindest thing you can do is put the bike (and yourself) out of misery. But parting it out can give new life to many other bikes out there in need of parts that are no longer available. Best of luck.
 
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