TOPIC:

With the wasted spark system these bikes use, that being 1-4 coil fires both 1&4 plugs at the same time but only one cylinder is in compression producing power. The wasted spark, in the other cylinder is just that, wasted. But both plugs need to be ground to the engine for one to fire. Performed the test as I suggested... also smell the plugs for the presents of gas...

Getting back to my original reply... fuel,spark, compression... you need all. If you have all it will run... once running you can tune...

So with your voltage checks.
It appears to me that your coils aren't charging.
The wire coming from the points is not grounding when it's points are closed.
If it was grounding, the closed points coil voltage would be 10.8 and 0.
Open points coil voltage would be 10.8 and 10.8.
But yours is 10.8 and 10.8 on both open and closed.. So your points when closed are not grounding. Which means your coils are not charging.

You can get one of your coils to spark by taking a small length of wire.
Turn on the ignition.
Hold one end on the engine case and the other end to the coil terminal for the POINTS.
(Do not touch the coil terminal coming from battery with this wire.)
Pull the wire off of the engine case. When you do this the coil will fire--spark plugs will fire.

You can use a test light instead of a jumper wire.
Clip on the coil's points terminal and touch the engine case with the test light.
Remove the test light from the engine and coil/plugs should fire.

Do another voltage check.
Both ignition points closed
Ignition on
DC 20v on meter
negative meter probe on negative battery terminal
positive meter probe on coil points wire terminal.
take a reading
Move the positive meter probe to the points wire terminal on the ignition points
take a reading

Check the other coil as well.

F64 wrote: So with your voltage checks.
It appears to me that your coils aren't charging.
The wire coming from the points is not grounding when it's points are closed.
If it was grounding, the closed points coil voltage would be 10.8 and 0.
Open points coil voltage would be 10.8 and 10.8.
But yours is 10.8 and 10.8 on both open and closed.. So your points when closed are not grounding. Which means your coils are not charging.

You can get one of your coils to spark by taking a small length of wire.
Turn on the ignition.
Hold one end on the engine case and the other end to the coil terminal for the POINTS.
(Do not touch the coil terminal coming from battery with this wire.)
Pull the wire off of the engine case. When you do this the coil will fire--spark plugs will fire.

You can use a test light instead of a jumper wire.
Clip on the coil's points terminal and touch the engine case with the test light.
Remove the test light from the engine and coil/plugs should fire.

I’d like to learn this diagnosis method but in you direction to the op you didn’t tell him to test with points closed... he tested as you directed with points open and is getting the readings your mentioning... 10.80 at both primary positive and negative... did I miss something

I’d like to learn this diagnosis method but in you direction to the op you didn’t tell him to test with points closed... he tested as you directed with points open and is getting the readings your mentioning... 10.80 at both primary positive and negative... did I miss something[/quote]

One set of points will be open. The other will set will be closed.
So.. the set open will have the same voltage for both terminals, but the closed set....different voltages.
There is a possibility that both points could be open at the same time. Which would give the same voltage for all combinations.

Ok ill give the wire method a try to get the bike started up. So if the points when closed are not grounding, what might be an appropriate fix? Just change out the wires coming from the points?

F64 wrote: One set of points will be open. The other will set will be closed.
So.. the set open will have the same voltage for both terminals, but the closed set....different voltages.
There is a possibility that both points could be open at the same time. Which would give the same voltage for all combinations.

My running bikes both have dyna S ignition, but my ‘76 project will stay points for now... this is a good experience for me... how easy would it have been for the op to get both sets of points open to get the consistent voltage readings he’s getting...

We have to find out where the fault is first, but replacing the wire from points to the coil could be a possibility.

The op mentioned he replaced the coils... could it be the coils are the wrong ohms?

My running bikes both have dyna S ignition, but my ‘76 project will stay points for now... this is a good experience for me... how easy would it have been for the op to get both sets of points open to get the consistent voltage readings he’s getting...[/quote]

I'm not sure how easy it would be to have both points open at the same time.
I'm checking the service manuals right now.

F64 wrote: We have to find out where the fault is first, but replacing the wire from points to the coil could be a possibility.

Just got the readings you mentioned. At the points terminal on the 1-4 coil I got 12.60v and when I moved the positive node to the points wire portion I got a similar reading of 12.56v

Somewhere on this I am getting lost. Perhaps it is in the verbiage. I have never heard this diagnosis explained in this fashion.

Rick H.

The points wire is fine.
Move the positive meter probe to the points plate.
Negative probe on negative terminal
photo: Patton