No spark, some ideas?

Finally got to the point where I am ready to start my barn find.
Cleaned the carbs, oil etc.
I have power, lights work but no spark. At least I cant see it. I have the plugs out and hanging by the wires but I cant see any spark. Thought I would put fuel to it and see what happens. Nothing. Whats the proper way to check for spark?
Electricity is not my strong point by far. Where do I start looking.
Sorry for the dumb question.
Any help is appreciated.
Thanks MikeM

Remind us again what bike this is, some of us have short memories !
Yellow S ?

First thing is, what ignition system is in it. Std points on the cam ?
Then check that you have power going to the points - ignition switch works ?
(And the first thing - is the battery connected, and charged).

To see you have spark, the usual way is to take out both plugs, with plug wires still attached, lay them on the metal of the head fins kick over and watch for spark across the gap. Don't get hands near them - and make sure there is no spilt gas around......

Opethiselps.

You must ground the outside electrode to the head/jug.

You have a 72, right? It most likely has 6V coils hooked up on series and a ballast resistor. Get a good ohm meter and check the resistance of the coils, somewhere around 2Ω from one terminal to the other. Terminal (either) to coil output (plug wire) around 9KΩ as I remember. Check ballast resistor, I don't know what that will be, I don't have one. Check voltage to coil -, should be very near battery voltage, ignition on. Check voltage from battery - to coil - with ignition on, should be very minimal, much less than .5V. If more, you have resistance in the circuit from battery to coil. Check resistance of ignition switch, should be less than .1Ω. If not take apart, clean and lube with de-ox.

Or hot wire the battery directly to the coil - and see if you have spark then.

Is your timing right, what kind of ignition, AAU or electronic. If electronic, suspect.

Previous suggestions too.

Dave
69S

MikeM said:

Whats the proper way to check for spark?

Click to expand...

Does it have points, or electronic ignition?

The coils appear to be non-standard? Are there any markings on them to identify which type/voltage they are?

Is there any voltage getting to the coil [-] terminals (original positive earth/ground electrical system polarity) ?
The original 1971 points ignition system would have had two 6V coils fed through a ballast resistor although not shown on the wiring diagram the wire from the ballast resistor to coils is white/violet.

DogT said:

You have a 72, right?

Click to expand...

1971

Thanks for the replies.

1971

coils are non standard, I have no idea what they are.
new battery, connected and the lights work.
Dual points ignition
Timing? Good question.
My electrical background is non existent. I guess I need to decide if I am in over my head.
Time to step back and look things over.

Need to clean the point surfaces by inserting a little emory cloth 320 grit or finer. When cars/bikes sit for long periods the points get a coating on them and will not make a good electric connection. Been there done that.

You say you have the plugs hanging by their wires when you kick it over and see no spark.

Did you see that two people have told you that the plugs need to be grounded against the head or they will not spark?

Please have an assistant ground the plugs while you kick it and look for spark, and no, assistant will not get shocked if they just hold the threaded portion of a spark plug against the head.

Then report back if you have spark or not, a dark garage helps.