Possible weak spark?

Hey all. I was given a 79 KZ750b. I've never worked on bikes so I thought this would be a good learner. I ordered and did the carb rebuild. Ordered a new batt and changed the oil. First try nothing. Used the manual and determined the ignition coil was bad. Would have replaced anyway due to a break in the spark plug wire. Installed that and gave it another shot. Figured out the resistors in the caps were fried. Ordered and installed new caps from NGK. Tried again still no spark. Checked another forum and decided to clean the points. Finally spark at the points! New fuel after cleaning the tank and rebuilding the petcok. A couple of chugs and pops but no fire. Checked spark at plugs and seemed a bit weak but was there. Couple shots of starter in the air box. Still nothing. Put battery on the charger and scratched my head for a while. Thought maybe timing was off. Fiddled with advancing and retarding. Still nothing. Noticed the spark at points seemed weaker than at first. Checked spark at plugs. Almost nothing. Hmmm. Put battery back on charger and figured I would ask a higher authority. Any help would be greatly appreciated. Would love to get this bike back in the wind.

Did you use the instructions in the Kawasaki Service Manual to set the points? Ed

Need to pick up a gauge today. Don't really know how to adjust but will use the manual. Wondering why one day spark the next day not so much. Do we have to do the captcha thing every time?

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.

These bikes have a 5000 ohm, non-replaceable resistor in the sparkplug caps. They go bad from heat, vibration and age. New ones are available at most Japanese motorcycle stores, or through Z1 Enterprises, Inc. - Specializing in Vintage Japanese Motorcycle Parts, including New Old Stock & aftermarket parts. www.z1enterprises.com is their website.

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.

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)

Thanks for the suggestions. I already tested and replaced the coil. I will test it again just to be sure the new one is good. I will definately go through all the connectors too. I just picked up a feeler gauge and will check points when I get home. Thanks for the info. I will keep u posted.

Tho an wrote: Thanks for the suggestions. I already tested and replaced the coil. I will test it again just to be sure the new one is good. I will definately go through all the connectors too. I just picked up a feeler gauge and will check points when I get home. Thanks for the info. I will keep u posted.

Is it a new coil or a used one? Z1 sells a good one for $36. You definitely want to get a new coil.

Also: replace the points and condenser. Z1 sells those.

Last: check timing advancer to make sure it is working right, many sieze up from rust over time.

FYI: there is now way to accurately test a bad coil. They arc from high voltage and many only do it when hot. You don't have the equipment to catch that, best to get a new one.

www.z1enterprises.com/ItemDetails.aspx?i...zuki&item=EM24-72451

It's a new coil from z1. Just checked input voltage. Only down .03 vdc from battery. Just checked points, fit .508 mm through at max open. It should be between .3 and .4mm right? PO sure stripped these adjustment screws. Will try backwards drill bit on those.

Well. Fixed points gap. Set timing using ohm method in MSM. Great spark at points and plugs now. Hooked tank back up and. Nothing. Guess I'll go back through the carbs again. Thanks for all the help. I'll keep y'all posted.

Inspect the ignition coil sparkplug wires for shorting to the bottom of the gas tank, this can happen and have you throwing things. You might have to double insulate those wires/leads.