No Spark on my 76 KZ650

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

Howdy all! I'm new to the forum and I'm sure it will be fun!
THought I'd post the problem I'm having with my 76 KZ 650 to see what you think...
Basically, the problem is that there's no spark at the plugs.
The battery is fine. There is spark at the points, and they are not burned out. All the fuses including the main are fine. But no spark.
I find it highly unlikely that BOTH coils are shot. I have checked all 4 plugs for a spark, and nothing.
Even though unlikely, I would like to check to see if the coils are functioning. Is there a way to check the coils without electrocuting myself?
Any ideas or comments would be greatly appreciated!
Sincerely, J.F.!

Robby · Dirty Old Man Joined: 16 May 2002 Karma :

If you pop them down to your local bike shop they should have a coil tester.

Alternatively get a fresh length of HT lead, plug one end into the coil and hold the other end close to the cylinder head. Crank the engine and see if you see any sparks.

Also check your earth connection - could have badly rusted at the frame. Try running a direct earth back to the battery.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Yeah, sounds very like a bad earth, classic problem with Zeds.

Either that or the condenser(s) are knackered. To test then , switch the ignition on then move the closed set of points apart with a biro or something, if a spark jumps the gap, your condensers are shot. If unsure, just replace them, they are cheap.

You can test the coil windings using a multimeter, readings would be found in a workshop manual (a worthwhile investment if you own a bike of this vintage.)

One thing that doesn't follow is that if you are getting a spark at the points, there should be a spark somewhere else too (the spark at the points and the one at the plugs are essentially the 'same' spark, just further along the circuit. So, if there is a spark, where is it earthing?

I would recommend cranking the bike over in the dark and having a look for sparks earthing somewhere they should not be
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

THanks for the replies! I can tell I'm going to have fun on this forum.
I did a lot of searching on the net for electrical articles relating to this bike, and I sort of came to the conclusion that my problem is most likely the condenser. Now that you've suggested that, stinkywheely, I think I'm on the right track because I checked all the earths (coil to frame, battery to frame etc) and none are rusted or corroded. I'm just going to buy a condenser, install it, and go from there. I'll let y'all know how it goes later in the week! Cheers, J.F.
PS I discovered that the factory coils should have a 4ohm resistance between the poles, and come to think of it, I was seeing the sparks at the points when they were in the OPEN position!! Kool, I think you've helped me figure it out!
CHEERS

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

All my mates who kept Z650s fitted them with boyer electronic ignitions and dynacoils (and usually a sealed battery for the boyer to chew on). Complete bastards to set up but maintainance free when done, the spark you get from them is TWICE as fat. Not cheap though.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

Well I put a new pair of condensers in and theres still no spark at the plugs. Gonna wait for my friend to test the coils with a multimeter.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

You just gotta break it down to its componant parts.

Your alternator charging coils generate current and load up the primary windings of the ignition coil in paralell with the condenser when the points are closed.

The points open, the charge in the primary coils drops away to earth. This generates a huge voltage in the secondary ignition coil winding which travells along the HT lead and earths accross the plug electrode.

SPARK

Something is stopping this happening or diverting the current to earth where it is not supposed to be.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

I want to eliminate the coils as the source of the problem. The wiring on this bike is so simple its hard to miss something. LIke I said, all the gounds are good. And I tried that trick of cranking it in the dark....didnt see any sparks ANYWHERE (the points cover was on btw)

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

I got a multi tester. I'm unsure of where to hook up the probes to test the coil resistance. There are 2 wires coming out of each coil, plus the HT lead. Does anybody know where to hook up the tester, or any other tests that I should perform now that I have a multi tester? Cheers.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

You really need a workshop manual, otherwise the readings are pretty meaningless anyway.

You should be testing between the two wires to test the primary winding (usually tens of ohms) and betwen the HT lead and earth to test the secondary winding (usually kiloOhms). The earth is usually where the coil bolts onto the frame.

Sorry, I don't have a manual and can't help you with the exact figures.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

I phoned every book store and bike shop in town for the manual, and it's not in stock AND out of print!!! I've gor great luck eh!! Saving grace is that the public library has ONE copy, so I will borrow it from them.
I hooked up the testers as you said, and between the two wires showed 0ohms. Between the HT and the ground showed infinate ohms. As far as what I can tell from what i've been able to read on the internet, that indicates a shot coil, HOWEVER I'll wait until I get the manual to make a decision...
Cheers, JF.

Big Pete · Spanner Monkey Joined: 18 Jul 2004 Karma :

check on ebay, there are often Haynes etc on there, usually cheap.
____________________
Trust me, I`m an engineer
GarageOfPower.co.uk

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

you can buy one online HERE
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

Hello, I was able to grab myself a Haynes manual last night. Lots of good info in there, including how to perform electrical tests. So I checked the coils properly, and according the manual they are within specifications. Now I guess I will have to go through basically every switch and wire until I am able to trace the problem. This is not going to be fun...

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

You have my sympathy. The wiring on old jap bikes is a fucking nightmare, I am doing up a vintage suzuki, I eventually lost the rag with it and tore the whole loom out, I am making a new one to my own design.

Top tip. Your computer is equipped with MS Paint, this allows you to draw boxes and straight lines in all colours. Spend an hour doing yourself a full-colour wiring diagram, in your case, I would just do the parts relevant to the ignition/charging system. Laminate it and pin it to the wal in the workshop. Makes things a lot easier to visualise and spending the time doing the diagram helps you understand what is going on.

Good luck!

This is the one I did for my Jawa 350 (nothing like the zed, just to illustrate the concept):
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Johnny Forgotten · Derestricted Danger Joined: 02 Aug 2004 Karma :

That's not a bad idea at all! I was able to acquire a manual at the library, and it has all the wiring diagrams in it. The hard part is going to be tracing out where the problem is. According to the manual, the ignition switch is the first place to start. I tested the coils with a multimeter, and they checked out as OK. So....I'll look at the switch etc etc until I find the problem. The manual is pretty god in that it gives all sorts of tests to do, and since it's for my specific bike, it gives the actual wire colors, contacts etc. I'll see how it goes over the next week or so.....