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Kill Switch 400/4

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smoothoperator:
I'm researching this topic and finding that there is a lot of information, so I'll keep looking. In the meantime could anyone shed some light on a couple of points? Current situation is that kill switch doesn't kill the engine in either of the off positions. Can I test its function without actually firing the engine up, which is tricky at the moment because of intermittent fuel overflow. I have a multi meter. I haven't found a black/white wire in the headlamp shell as yet. As I understand things this wire routes to the coils, so with the ignition on I'd expect to see a voltage, but where to measure it? Looking at stripping the r/h switch unit but even removing this is looking tricky to me at the moment, with wire tight into the handlebars, throttle cables to disconnect and handlebar to remove there is quite a bit to learn. I'm a bit baffled at the moment, any help would be appreciated.

Just noticed the loom from the handlebars routes to underneath the tank so I can eliminate searching in the headlamp shell.

Lobo:
You’re on the right track; you need to place the Red probe onto the B/W wire under the tank, and the Black probe onto the battery negative (or KNOWN good Earth). (Black circle in the pic). The ignition will need to be ON.

The B/W wire has two possible connectors you can use; either the one in the ‘boot’ forward LHS of the tank (Blue circle in the pic).... or by the coils where the feed splits (Red circle in the pic). (you do not need to disconnect the connectors, tho’ a slightly lower voltage reading will result)

An odd failure: my early guess is that the kill switch (or it’s wiring) has failed in the past, and the PO has simply directly connected the coils to the ignition, bypassing the kill switch circuit.

To test the Kill Switch functioning, you’ll need to disconnect both its Black and B/W connectors within the boot. (These are both within the Blue circle).
(To set the meter select  the lowest Ohms range, and touch the probes together - you should see close to 0 ohms.)
Now put the probes across the Black MALE and B/W FEMALE connectors of the kill switch, and check its continuity in the OFF / ON / OFF positions. In OFF you should see Infinite ohms (open circuit), and in ON you should see close to 0 ohms.
Wiggle the handlebars / loom whilst doing this check, see if anything changes... bad loom etc.

The Kill switch is indeed a pain to remove / service. As a starter for 10 it might just be worth shooting a good squirt of WD40 into into any nearby switch orifice!

Good luck...

PS - whilst the safety implications are obvious, in this current state of ‘permanent’ Kill function ON you may burn out a coil / flatten the battery when the ignition is ON & engine not running for any length of time.

McCabe-Thiele (Ted):
Aside from your mates overtaking you and activating your kill switch it has always baffled me as to its purpose.

I do not recall any of my Mopeds,Scooters or British Bikes having such a device though my memory could be defective. That said if its fitted I want it to work!

mike the bike:
It's very unlikely that the kill switch could go faulty in this way.  I've had one open circuit,  but never a short circuit.
It's more likely a previous owner has been meddling with the wiring, perhaps to repair an open circuit switch.

smoothoperator:
Thanks guys, great help for me to test this now. Meanwhile I have found a smoking gun. I have put an image in below along with a couple of pic's of the coils. There is a disconnected black wire from the r/h handlebar and a likely looking home for it, both circled. The female circled is a double connector which has 1 black/white and 1 black - although the plain plain black is difficult to see in all the grime.

There are 2 other empty females in the bag but these are orange/white and light blue/white.

The only dodgy bit I have arrowed as it is very poorly connected and is thinner than the rest of the wires. This might be a red herring/future issue/no issue.

https://photos.app.goo.gl/AvCtaW7HwqH5YLcx6

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