could use some help starting on a kz750 ltd projec

HI, im new to the forum. I just got a 1981 kz750 ltd, and it needs some love to say the least. I've always had project cars and am pretty handy, but I've never done a bike this old before. Im going to try and build a cafe racer style bike I'm really hoping I haven't gotten in over my head. The bike appears to be all there, but I'm already experiencing wiring problems. I haven't even been able to try to turn it over because I'm getting no response from the start button. Does anyone know where I can find a good service manual or some wiring diagrams? I figure that would be a good place to start. Any suggestions on what could be preventing it from even trying to start would also be helpful. I got the bike on Craig's list so I know very little about it. The guy rewired it and I'm hoping he didn't screw anything up

Are you pulling in the clutch lever when trying to start it? Ed

yeah i held the clutch, its in neutral anyway but i tried it. it doesnt do anything, doesnt even make a sound. i think maybe the starter relay is bad. i noticed quiet a bit of rust on the nuts holding the wires on. figured maybe thats creating a bad connection or something? but there are several wires not connected to anything on the bike and i have no idea what they go to, so maybe its as simple as something not being connected. but i traced the wires and none of them seem to be related to the starter.

I am new to this too, but had issues getting my 550 ltd started also.
I had success when i checked my battery was fully charged 12v and then opened the headlight cover and located the hot wire from the ignition switch and terminated it with the yellow wire that goes to the right hand control isolator switch and starter push button. As mentioned the clutch lever needs to be held in as there is a safety lock out switch, I cable tied the lever closed whilst testing to make it easier.
It would pay to check all connections for good contact and put a meter on switches to test operation.
Hope this helps but I am trying to learn as I progress on my project also so I am sure there are plenty who could help further if needed.
I have attached a picture that could be your bikes wiring.

The 1981 750-Ltd-4 is a KZ750-H2. The 750E wiring diagram linked above may have some differences. Here's a site w a manual & wiring diagrams. mbsween.bike-night KZ750L3 page
Scroll down & click "The Bible" link.

Note for the 750-Ltds: 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. search tags mbsween KZ750L3

You can get a manual on eebbaayy: search for KZ750 manual. Kawasaki factory service manuals have a model application chart on the back cover, so make sure yours is included. The 750-Twins & Shaft drive models are different from your bike.

No eBay APP ID and/or Cert ID defined in Kunena configurationAbout as cheap as it gets on eebbaayy.

I didn't realize that there was a switch in the clutch, good to know thanks. martin, thanks for the wiring diagram that will be extremely helpful. knowing the H2 designation is also quite useful, I never would have known which diagrams to look at. I have been tinkering around, and I did find a bad connection going to the starter relay. I stripped the wires and reattached them, and i am at least getting some sort of response from the starter button, although I'm not sure it is a good one. It doesn't try to start, it doesn't make a sound. But now when I try to start it, the lights dim. That is at least a sign power is being routed somewhere, i suppose. Maybe the battery is just too weak? I charged it up but it is an old battery and probably isn't much good. I just hoped it would work since it had enough juice to turn the lights on. I guess it could be another bad connection somewhere, though. Any ideas, anyone?

Also, I tried hitting the starter button without holding the clutch, to see if the lights would still dim. They do, so I guess either I have a short somewhere, or the switch attached to the clutch lever has been bypassed somehow by the previous owner

I'd open up the right handlebar switch "Pod", and look for crumbled solder joints on the switches. The switches there are for run/stop and start. If you find bad joints, here's how to repair them:

Repairing crumbled switch and light bulb socket soldering.

Some of the older Kawasaki's, and possibly the other brands of motorcycles may be experiancing crumbled or failed switch and light bulb factory soldering jobs. Here's a repair procedure:

When repairing soldered wires on motorcycle switches or light bulbs sockets, have the following on hand:

1. A 25 Watt soldering iron or one that the wattage can be adjusted.

2. Rosin core solder.

3. Rosin flux or soldering paste (Never use solder or soldering paste designed for plumbing work, as it contains an acid that will corrode the electrical joint, ruining it).

4. 91% rubbing Alcohol, or 70%. The lower percentage will clean up flux residue, but not as good as the higher percentage stuff. Acetone is also a good soldered joint cleaner, but’s its very flammable.

5. A cut down ½” paint brush, or acid brush for scrubbing the repaired solder joint.

6. Clean rags or paper towels

7. A damp sponge to keep the soldering iron tip clean.

8. Some “Solder Wick” a braided bare copper wire designed to collect heated excess solder, aiding in joint preperation, available at electronic supply stores.

9. Some wooden toothpicks.

10. Small Hemostats or clip on heatsinks.

A. Before soldering, “Tin” the soldering iron tip by plugging it in or turning the iron on, allowing it to get to operating temperature(2-3 minutes).

B. Unroll about 3” of solder from the roll of rosin core solder & then using a clean rag or paper towel moistened with Alcohol, wipe the unrolled solder, removing the finger print oils that will create a poor solder joint.

C. Apply a small amount of solder to the now heated soldering iron tip, wiping the excess off with the wet sponge or rag, keeping a thin layer of solder on the soldering iron.

D. The soldering iron is now ready for use, but before applying the heated tip to a wire, wipe the tip on the damp sponge or rag, this removes any oxidized solder and makes for a much better connection.

E. If the joint to be repaired is grey in color or appears “Crumbled”, apply some rosin soldering paste or flux to the joint with a small toothpick of screwdriver, and then apply the soldering iron tip for a few seconds.

G. The fluxed joint should clean up, allowing for a better connection. If no luck, use the solder wick to remove all traces of the old solder by apply in it between the soldering iron tip and the bad joint.

H. Hemostats and clip on heatsinks will be used to prevent the wire insulation from burning, overheating & pulling away from the connection.

I. Apply a small amount of flux to the joint to be repaired & then a very short duration of heated soldering iron tip & solder(like a few seconds or so).

J. Clean off the repaired joint with the brush & rubbing Alcohol, the newly repaired joint should appear clean and bright, almost as if it were polished, with no voids or holes.

This information comes from years of missile test cable and equipment assembly, when I worked at General Dynamics/Convair division in San Diego California, on the BGM-109 Tomahawk and later on the AGM-129 Advanced Cruise Missile. This was from 1983-1993.

Another procedure to do, to make your motorcycle more reliable, is to do this:

Cleaning Motorcycle Electrics

Get some of the De-Oxit DN5 electrical contact cleaner and figure on spending a good day going from the front of the bike to the back. It’s a plastic safe cleaner/preservative. www.deoxit.com is their website, and can be purchased at most electronic supply stores.

On the older Kawasaki's, and other makes, a majority of electrical connectors are inside the headlight housing requiring removal of the headlight, then the fun begins.

Do one set of electrical connectors at a time to avoid mixing up what connects to where. Usually disconnecting, spraying with De-Oxit DN5 and reconnecting is about all you'll need.

However, when encountering the green crud of corrosion, a brass wire brush may be needed on the pins you can reach. Some 400-600 grit wet and dry sandpaper strips rolled into a tube should reach the male and female pins in the more difficult to clean connectors.

Smoker’s pipe cleaners, cotton swabs and wooden toothpicks work as cleaning aids.

Really small electrical connectors may require the use of a welders tip cleaning tool assortment.

Most pins in the connectors are coated with a thin plating of tin, and others may be nothing more than copper or brass.

If moisture is added, the resulting corrosion lowers the voltage/current being carried causing dim lights, slow engine cranking, slow turn signal response and lower input voltage to the ignition coils resulting in weak spark.

The left and right handlebar switch pods will need attention too as they have circuit functions like turn, horn, run/stop, and start. If you discover the soldered connections at the switches are crumbling, I’ve got a repair procedure for this, just ask.

Usually a spritz or two with actuation of the switch is about all needed for these switches unless corrosion is detected and then careful disassembly is required.

The ignition switch may or may be not sealed to allow spraying the internal contacts. I urge caution if attempting to open this up as springs, and ball bearings may fly out never to be seen again!

If your bike has the older style glass tubed fuses, I suggest replacing them as vibration can cause internal failure. AGX is the type used, and most auto parts stores can get them for you. I replace my glass tubed fuses yearly, before the riding season begins.

Clean the fuse holder clips, looking for signs of overheating(discolored insulation, signs of melting). I use metal polish on a cotton swab, followed by spraying another clean swab with the De-Oxit DN5 and then rubbing the inside of the fuse clip.

All battery cables must be clean and tight for maximum current transfer. Check the cables going from the Negative(-) battery terminal/post to the engine mounting bolt

Also the one going from the Positive(+) terminal to the starter solenoid and from there to the starter motor.

If any battery cable feels ”Crunchy” when flexed, replace it as possible corrosion is inside the insulation.

Each "Bullet Connector" will have to be sprayed to ensure good connectivity, especially the ones going to the energizing coil of the starter solenoid.

The alternator output “Bullet Connectors” are usually behind the engine sprocket cover and will need inspecting and cleaning too.

The turn signal light sockets will benefit from a spritz from the contact cleaner along with the tail light/brake light socket.

Some brake light switches can be sprayed on the actuating rod, with the spray running down inside to the electrical contacts, others may be sealed requiring replacement if the switch is intermittent in operation.

Some people put the Di-Electric Grease on cleaned terminations/connectors, I don’t, as I’ve read/heard it can cause problems when it gets hot, actually insulating the connections, so the choice is yours to use or not.

I think I've covered about all of the electrical systems on the bike.........


“I spent a weekend going through every electrical connection and switch on the bike with a little scotchbrite pad and DeOxit - what a difference! Everything was brighter, gauge backlights, indicator lights, turn signals, I was getting a nicer spark, it fired up quicker, etc. Well worth my time. WELL worth it! “
From a forum member at www.kzrider.com


Re: Cleaning the many and various Motorcycle electrics.
I used the De-oxit D-5 spray on all the electrical connections of my 78 Kz1000 that had sat for twenty years .

When I parked the bike in 92 I was starting to have troubles with some of the electrical system, but after pulling everything apart and giving it a spray , reconnecting the connectors and working them back and forth a few times, then gave them another shot of spray to wash them off before the final reconnection.

Everything still works perfectly and has for over 7000 miles this year.

I am extremely happy with the results , a lot of the connectors were green when I started and after the cleaning they looked new ( shiny gold )

I found the Deoxit D-series, D-5 spray in a 4 oz can at a big electronics store called Frys in Illinois, don't get the small cans at Radio Shack , they are different and meant for computer type stuff.

store.caig.com/s.nl/sc.2/category.188/.f

Trust MFolks , the guy's a true rocket scientist and really knows what he's talking about.
JD

Use Deoxit DN5 on new or restored electrical contacts to condition them against future corrosion. Deoxit DN5 dissolves oxidation and corrosion on metal surfaces, fills in microscopic gaps and reseals surfaces for better electrical conductivity.

VOC and RoHS compliant
Nonflammable, quick-drying, non-dripping, and safe on plastics
Reduces arcing, RFI, wear and abrasion

Brand: Caig Laboratories
Model: DN5S-6N

Specifications: Net weight: 5.75 oz. (163g)

Testing Kawasaki Ignition Coils For Input Voltage

When voltage testing Kawasaki Ignition Coils, the following needs to be done:

1. Remove the fuel/gas tank to access the coils.

2. Fully charge the battery.

3. Using a multimeter, set it up for VDC(Volts, Direct Current), range of 20.

4. Turn on the ignition switch and the run/stop switch to “Run”.

5. Put the multimeter’s RED probe on where the red or red/yellow wire goes on the ignition coil.

6. Put the multimeter’s BLACK probe on either the battery Negative(-) post/terminal or a good frame ground.

7. You should be able to see battery voltage at the ignition coil connection, but this depends on the current draw of other items in the same circuit.

8. If the tested voltage is down to 8-9 volts, you probably need to clean the many and various electrical connectors.

9. To check the spark output at the sparkplugs, use Ignition Spark Testers. Instead of grounding the sparkplug with the sparkplug wire attached, looking for a spark. This method puts the IC Igniter and ignition coils at risk of failure due to high currents, and possible internal shorting.

thanks mfolks, that was my next step. I thought that could be an issue as well, because I tried again after checking a few more wire joints and smoke came from the that area on the handlebar. I would think either a solder point inside is bad, or i have a wire shorting out somewhere, right? The two screws holding the housing together are pretty rusted, one came out but the other stripped pretty bad. I'll have to get a screw extractor set or try to put some vice grips around it to get it out. I'll let you know what I find once I am inside

I got the housing for the start/kill switch apart, checked the wiring in there and cleaned it up a little.
Then I tried to start it again, this time I got a small shock when I pressed the button. Looks like I have a short somewhere, yeah?