Points ignition voltage output

[Knowledge]

For the first time in many years, I am tinkering with a scooter with points ignition

No spark.

What voltage output should I see from the green wire from the stator? I am only seeing 2.5v AC

[Chadley]

I might be wrong, but I’m not convinced you can tell much from a simple voltage measurement on the green stator output at kick-over speeds. I just measured mine using an AC multi-meter and found that it varied between kicks, most of the time I recorded about 2 volts but occasionally registered about 60V. I suspect this is due to the way the meter averages the signal.

What I do as an initial check is to measure the resistance from the stator green to earth with it disconnected from the junction box. With the points closed, there should be a complete short (0 Ohms) and with the points open you should see about 0.8 – 1.0 ohm, that is the resistance of the stator coil. Not much of a difference but with a decent meter, you can distinguish the two. That checks the points are operating, the stator coil is not open circuit and the condenser has not gone short circuit.

If that checks out, I’d check for continuity between the junction box and the HT coil to confirm that the stator is feeding the coil okay. I believe the green should connect to the terminal labelled ‘15’ on a Ducati coil and the other one that is labelled ‘1’ should be earthed.

You can do a basic test on the HT coil by disconnecting the green from ‘15’ and checking the resistance between the terminals. I believe for a Ducati coil, there should be about 10Kohm between HT output and either of the ‘1’ and ‘15’ terminals and there should be about 0.4 ohms between ‘1’ and ‘15’.

[Knowledge]

Thanks for the reply.

I have no idea what I did, but suddenly there is a spark. It runs (but not very fast)

I have now lost interest in my original question.