Cut Out Wire Resistance

[Paul_from_Thornbury]

winter model cut out at traffic lights last Friday, while waiting for recovery I had a quick look and disconnecting the green cut out wire from CDI it started, so having a look at that circuit today.
With the cut-out switch disconnected from headlamp block and the harness cut-out green wire disconnected from the CDI the green wire circuit is open circuit to earth, so the harness green wire from CDI to headlamp block is not earthed.
With the cut-out switch reconnected to the headlamp block, and the harness cut-out green wire disconnected from the CDI the green wire resistance to earth is 1824 ohms and 700 ohms with cut out pressed.
As soon as the harness green wire is reconnected to the CDI the resistance is down to 350 ohms to earth and the engine wont start with that low resistance. it goes to about 100 ohms with cut-out pressed.
With the harness wire disconnected the spade on the CDI to earth is also 350 ohms but the engine will run?

According to Stickys book the green wire to earth can be as low as 380 ohms for Indian stators so this looks in the right ballpark.

Tried another CDI with same result.
What are resistances I should be seeing and why is the cut-put switch causing the issue when the resistance to earth is the same whether its connected or not?

[CHRIS in MARGATE]

Infinity when not pressed. A total disconnection.

0 ohms when pressed.

[Paul_from_Thornbury]

So with the cut-out switch disconnected at the headlamp block the green harness wire measures 350 ohms to earth and the engine runs. Touching the cut-out green wire to the block it cuts out.
With the cut-out wire connected in the headlamp block the resistance to earth on both those green connections is still 350 ohms but the engine wont run.

Where should I be measuring infinity?

[Paul_from_Thornbury]

ive ordered another cut out switch, but from a measurement perspective the problem does not make sense.
If anyone can give me the reading of the green wire in headset to earth it would be appreciated, with and without the cut-out button pressed.

[CHRIS in MARGATE]

Disconnect the green wire at the CDI that goes into the wiring loom and up to the headset cut out switch. Put 1 lead of your meter on a good known earth and the other lead on the green wire that you have disconnected.
With your meter set to ohms/resistance you should see NOTHING. Activate the kill switch and you should see the reading now move across the scale on an analogue meter.
If you are using a digital meter you should see ------ or error or 999999. This is infinity meaning NO connection.
When you activate the kill switch the meter should go back to 0 (ZERO) or perhaps 1. This is a perfect resistance reading indicating a perfect connection.

If with the green disconnected at the headset block you have zero or low resistance then the green wire is shorting out to earth on the frame or against another wire in the loom.

You can test the switch by moving your meter up to the headset end and repeating the test there with one lead on a good earth and the other on the wire coming from the switch itself.
Repeat the tests with meter set to ohms/ohms x 100/ohms x 1000 etc. Always tap the leads together first to ensure meter working.

Any problems please ask but I am temporarily 10 hours ahead of you. Others will soon be along.

[coaster]

I agree with what Chris says, there should be no significant reading to earth on the green wire to the headset. The problem is electricity track to earth across the plastic insulation used within cutout switch and wiring connector block, which is worse in damp conditions. WD40 MIGHT improve the situation. Indian ignition switches are notoriously bad for this problem

[CHRIS in MARGATE]

Any update?

[Paul_from_Thornbury]

It was the cut out switch. As said above, the resistances all looked good, but with the cut out in the circuit it would not run.
Replaced with a Casa cut out switch.

[CHRIS in MARGATE]

Well done.