Dove oil valves

[BruceB]

I am a bit puzzled but this is nothing unusual. I have bought and am currently fitting a dove oil valve to my G12, having had a manual valve fitted by a PO that I have several times forgot to switch on. (and which I also recently found was not brazed on but just stuck on with a bit of glue)
I don't use the bike often enough, usually because it is broken again!, to stop it wet sumping over time. Anyway I don't want to start that argument again.
My question is this. I have an alternator fitted distributor fitted model which I have rewired to neg earth 12v. I therefore bought the coil ignition version with a relay. Maybe I am being stupid but the relay only works when the ignition is switched on and the switch operates the relay breaking the ignition circuit, when the oil switch is on the relay drops out and the bike can be started. It follows then that failure of the relay means the bike can be started with the switch off.
What I don't understand is that if the switch is wired into the wire going to the points and grounded no relay is then necessary. The bike cannot be started if the wire is grounded when the switch is off and the only failure point is the switch itself.
Can anybody thing of a reason why this a bad idea? It removes another component (the relay) and extra wiring to simplify the circuit and only creates the same situation as if you leave the ignition switched on anyway, most of the time the wire is grounded when the points are closed, it just stops a spark when the points open as it is already grounded?
It seems so obvious that I am questioning myself as where I am being stupid

[BruceB]

Just so it is clear, can I not do this?

dove.png

I am struggling to think why not

[Duncan]

Do you have the correct switch, a mag one would go to earth, a coil one should be part of the circuit (no circuit when the tap is closed and a circuit made when the tap is open)?

[BruceB]

Mine is a coil one and includes a relay to wire into the coil ignition circuit. The switch itself is open circuit when open and closed circuit when closed, but the wiring diagram shows this as well for the wiring into the coil supply as exactly this.
I just don't understand why the switch simply earthing the CB circuit would not work just as well as the mag version earthing the mag. Not sure what the benefit of the relay actually is.
I may call the company tomorrow and ask the question but if I install it as shown above I can't see why t would not work.

[Cerberus]

An observation would be that with the circuit above, if the oil switch is closed and ignition switched on, you've effectively shorted out the battery, which is not generally considered a good idea.

[Groily]

That would be my observation too. And is why, I imagine, the good Mr Dove designed the battery/coil version with the relay.

Like any maker of things, he has to think 'What happens if the owner forgets to do something basic?' (As in, 'switch off the ignition' in this case).
Given that in an extreme scenario the bike could conceivably go up in smoke . . . . and given that people are notoriously quick to litigate these days because nothing is ever their own fault . . . . It's hard to criticise the approach taken.

That said, I ran one coil ign bike for a long while with a 'simplified' cut-out exactly as per the diagram, running from a home-made tap, and it was fine.

[Mick D]

Hi

With regard to the observations by Cerberus and Groily, and on an unmodified bike - leaving the ignition switched on on a CB configured bike would result in the battery draining through the coil / points in around 80% of shut downs, (an approximation of the time the points are closed). If they were liable to burst into flames I think we would be more aware of that by now

Can't see the point of the relay unless the power is tapped upstream of the coil.

Bruce - Why not post the wiring diagram or a link to it?

Regards Mick

[Stan Palmer]

Hard to comment without a complete diagram for both suggestions. Perhaps the relay drives an indicator ?
Stan

[BruceB]

The diagram here shows the suggested wiring with the switch. The relay is NC and the switch is opened when the oil valve is closed which energises the relay coil and cuts off the coil supply. It can also be seen that if the relay fails or the connection breaks to the switch the bike will run with the oil switch off anyway.

coil.png

The diagram I put up earlier does not short out the battery, it is an earth on the distributor side of the coil which would inhibit the spark by making the opening points pointless (pardon the pun) by preventing the coil operating. The distributor is essentially shorted to earth except when the points open anyway.
The ignition being left on is no worse for draining the battery than if you leave it switched on anyway.
I am failing to see why I could not simply simplify the wiring by placing the oil switch as my original diagram and disable ignition by stopping the points being seen as open by the coil when closed?

[Stan Palmer]

Hesitate to say anything when expert like Groilly is on the case.
My 2P is that your scheme would work, the difference being that in the one case the ignition coil would be passing full current all the time you were fiddling about with other things while the ignition is on but oil closed, while in the other case all the system will see is a very small current for a relay coil. Of course we never fiddle with old bikes, it's one kick and away !
Fail safe is not always straight forward. In petrochemical and offshore it was always failure = trip, but the French didn't always do that with some notable results in the past. Maritime it was considered safer to risk an engine destruct rather than suddenly lose power in a heavy sea due to an instrument fault. Hence the use of voting systems for criticality of safety or cost. In the case of your relay, it seems better to let the engine run on in case of coil failure. It might have been nice to somehow indicate the failure at the next use of the switch. Sorry, I was a controls engineer so complication follows me around.
Stan