1976 KZ400 No Spark

Hi Guy's trying to get an old KZ400 to run before a strip down and restore and I have no spark

Firstly the coil seemed faulty as when I did an Ohms test between both plug leads I got no reading, Purchased a replacement coil and installed but still same problem, new coil tests fine on both circuits with multimeter. So far I have checked the below

1. 12v Power to Red Yellow wire going to coil checked OK
2. Points, cleaned set and tested OK, "Points haven't been replaced by me but they look in good condition" and test fine with test light

Is it possible a faulty condenser can cause no spark? that's about all I am left with, I have ordered one but as I understood a condenser is just basically a capacitor to absorb high voltage so your points don't burn out too quick can this cause no spark if faulty?

Cheers in advance

Have you load tested the battery? Only 12v at the coil is a bit weak. A good battery, good wires and clean connections should provide around 13v at the coil.
Also check the battery ground cable to be sure it is free from corrosion and that it has a very clean connection to the crankcase or frame.
The kill switch is set to RUN, right?

-Battery fine, i'm running from jumper cables from a car battery fully charged, headlight bright, would think that means my ground is good too....
-Kill switch functioning correct, if it was off I would not have power to the Red Yellow wire
-Have tested blue wire at coil with test light it flashes when motor turns so points seem fine just getting no juice out of plug leads from coil

Condenser seems to be the only thing left but I thought that only absorbed high voltage to save points burning out prematurely

Just learnt how to test plug caps, pretty sure this is my issue.....

Will report back

Please be sure that the car is not running when you try this. Its alternator output will fry your bike's electrical system .

Yes not in car just a spare car battery.

Alright so it's my resistor caps, guessing the high resistance burnt out the original coil too.
Anyone got an NGK Replacement Part Number or equivalent I can use and is the spec 5k ohms?

I wouldn't worry about cap resistance. If you just want to get it running before you tear it down to make it pretty.
Just use any plug wires and coil that works . You can change it out later.


.

Like Nebr_Rex said, any ole cap will do. If you are worried about creating rf interferance once the bike is running, you can use resistor plugs OR resistor caps OR resistor wires, but never more than one of them. You can also run without any of them

Had some spare caps off an old CB400T, as soon as I put them on I got spark, tried the old cap again zero spark :blink:

Anyways have ordered some NGK LB05F to use eventually

Defective plug wire?

Ohm-checked secondary loop (cap to cap)?




A non-conductive (defective) plug cap is one of the many possibilities whereby a break is created in the secondary loop which prevents plug spark.




Properly functioning secondary loop with
both spark plugs simultaneously firing:


Good Fortune!

Well hey I got a problem with a barn find kz400 S  .I get the bike it was locked up .So I  get in piston and rings  put it together something is hitting I find out valves are stuck .So I fix that problem I get it loose .then I find out starter button isn't working or on and off .So I cut wires and get starter and on switch working .My key switch seems to be working .I find out I have no spark to plugs .so I check wires and figure maybe coil is bad so I buy cool ,I still have no spark .I trace a plug coming out of magneto and find one side is hot other side of plug is dead .Soni straight hook up wires and take plug away .much to my amazement  I find  connection dead I'm puzzled .So I unhook wire red I think going into light blue and it's live again .I connect them back and it deadens both wires .what is going on here.i tested coil got two wires to that there hot .but I hook rest light to spark plugs wires I got nothing .Anybody know why I don't have fire to plugs help me out here thanks 

Stop.

Before you randomly chop up the harness anymore, put things back where they belong. The factory service manual has specific tests to diagnose such problems. Cutting wires and bypassing parts of the system just creates the possibility of more problems and will make diagnosis more difficult.

www.kzrider.com/modules/ServiceManuals/7...chablefullmanual.pdf