Normally-Open Kill-Switches & PAMCO

osteoderm

osteoderm

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Normally-Open Kill-Switches

I'm trying yet another "different" thing on my build, and am running into a potential problem with my kill-switch. I thought I'd separate this problem out into another thread. The basic problem is with a normally-open (N/O) kill-switch.

To start things out, a recent email exchange with Pamco Pete:

Pete,

I have a normally-open momentary-contact kill-switch which I would like to use on my PAMCO-equipped XS650. The switch is part of a cluster, not practically changeable to normally-closed, and I would prefer not to use a relay, ie., using the N/O kill-switch to energize a N/C relay inline with the red/white wire powering the ignition.
In other coil applications, my instinct would be to use the N/O switch to momentarily ground the negative side of the primary (PAMCO green) in order to stop the engine. Would this work, or would it fry the PAMCO? What would be the best way to proceed?

Thanks for your help and advice,
Click to expand...

Pete very quickly replied (and folks, buy PAMCO! It's worth it for the excellent service alone!):

That would work, but I do not recommend it for these reasons:

1. When you release the switch you may get a backfire.
2. If you release the switch before the engine has completely stopped, it will start up again.
3. If you forget to turn off the ignition switch, you could fry the coil and the PAMCO.
4. In the event of a runaway engine, you would have to hold the switch until the engine completely stops.
5. When working on other parts of the electrical system, you will have to remove the fuse for the ignition or risk frying the coil and PAMCO.
6. You insurance company would be unhappy if they knew because you would be tampering with a safety feature.
7. If someone else rides your bike, they may be unfamiliar with your setup, even if you instruct them and could screw up and have an accident. (see 6, above)

Pete
Click to expand...

First of all, I have zero disagreement with anything Pete says on this matter. His points are correct, thoughtful, and plainly-stated. However, I'd still like to get this to work somehow.

I could try to rationalize away a few of these concerns: It is my habit to turn always turn off the engine with the key, which takes care of items #3 and #5. If someone else is riding my bike, it's because it's not my bike anymore, which (sorta) takes care of #7. As for #6, well, let's not tell 'em about any of the "other modifications", shall we?

I can't see any simple ways around #1, #2, and #4. Pete is dead correct, and a kill-switch needs to a be a no-brainer fail-safe positive-stop. Just the kind of action a N/C non-momentary switch (ie, stock) kill-switch provides when wired in series with the ignition hot.

About that un-wanted relay: it seems counter-intuitive to rely on a device (relay) which itself requires power in order to cut power to another device (ignition). Besides, I'm trying to simplify things a bit here, not add more wiring back into the mix. But, if some sort of signal inversion will do the trick, perhaps there is a robust solid-state solution? A bi-stable latching relay?

Any more ideas, anyone?
 
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"I could try to rationalize away a few of these concerns: It is my habit to turn always turn off the engine with the key, which takes care of items #3 and #5. If someone else is riding my bike, it's because it's not my bike anymore, which (sorta) takes care of #7. As for #6, well, let's not tell 'em about any of the "other modifications", shall we?"

Well, this is where a lot of us go in the wrong direction. If you sell your bike and it has mods that involve the safety equipment (no front wheel brake, turn signals, brake lights, kill switch etc.) and the new owner has an accident, you could be held liable.

If you tell your insurance company about the mods you did to your safety equipment, then they may pass on insuring you, so you lie. Lying to your insurance company on an application for insurance is called insurance fraud. It's a criminal offense.

It all depends on the severity of the accident. Meaning, if there is any bodily injury or death, the insurance companies will take a closer look to try and reduce their exposure to potential claims.

If the other party in an accident is at fault, then their insurance company will attempt to lay some of the blame on you. That's called contributory negligence. IE: Someone rear ends you, it's their fault, but you have a non DOT approved tail light, so you contributed to the accident.

If you are at fault, then your insurance company will pay the claim from the other party, but then they may come back at you for insurance fraud if you lied on the application. If they come back at you and you did in fact commit insurance fraud, then they can sue you for the total amount that they had to pay out to the other party, including legal expenses.

So, why do you buy insurance for your bike? Because you can't get a tag without insurance, but keep in mind that screwing with the insurance company is worse than screwing with the DMV.
 
The tone of my words may have been misunderstood. Yes, I could "try to rationalize", and I'm sure many people do. Personally, I'd really rather not. Despite all my extensive changes, it has always been my intention to finish with full brakes, full lights/indicators, a legal inspection, and non-fraudulent insurance.

I am not in disagreement with any of Pete's comments regarding safety, liability, or responsibility.

However, my question is not one of getting around the rules; it is one of safely using a N/O momentary-contact switch as part of an effective kill-switch circuit. If this is just not possible, then I'm back to the drawing board.
 
"I have a normally-open momentary-contact kill-switch which I would like to use on my PAMCO-equipped XS650. The switch is part of a cluster, not practically changeable to normally-closed..."

I question this. There are a variety of micro-switches that are readily available. If you posted a picture or two of the cluster, including the insides of it, I or someone else might be able to suggest a switch that would work. No guarantees, but worth a try.
 
The switch cluster in question is a sealed CEV unit, KTM Part# 50311070000. Like so:

switch.jpg


The visible screws only mount the switch body to the bar clamp; the body itself is riveted closed, making modification unpleasant. For scale, those silver screws are about 1-1/4" apart. It's small. I'm wicked good with a soldering iron myself, but it would defeat the purpose of using a sealed stock-application switch like this to start chopping into it.
It's not that I love this switch cluster so much; it's just that I hate it much less than most others. :) I can see being forced into a separate conventional killswitch on the right side of the bike, in which case I would deface/blackout the marking on this one and/or disable it to avoid confusion.
 
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I think I still might be tempted to drill out the rivets, but you seem to know what you're talking about, so if you say no, then okay.

The other thing you could do is put the separate NC kill switch somewhere completely else on the frame, other than the handlebars, but pamcopete won't like that, and I'm not crazy about it either, especially after seeing hotdog's ghost rider video.
 
osteoderm,

Well, being as it is a requirement to have your headlight on when riding, why not just wire the ignition to the headlight circuit? You could then wire the kill switch to the PAMCO green wire as originally planned without some of the limitations, especially if you don't use it, but at least the kill switch would be functional.
 
Pete, your suggestion is probably as effective, and far simpler to execute, than the one I came up with at 2AM this morning... :doh:

kill_relay.jpeg


In normal use, the relay is never energized. Key on to run, key off to stop. The killswitch does nothing when the key is off.

With the key on, pushing the killswitch energizes the relay, interrupting power to ignition. Once flipped, the relay remains self-energized. Ignition power remains interrupted until either the capacitor/battery is drained, or the key is switched off. In neither case will the ignition see any power after the engine has stopped. The green wire is left alone.

Multiple N/O switches could be wired in parallel with the killswitch. Any kind/amount of conventional killswitch could be added in series with the keyswitch.

Obviously, the relay would need to be fused, and capable of passing and interrupting current up to that of the fuse.

Thoughts? I'm not settled on any of this, just theorizing so far...
 
The other advantage to wiring the ignition to the headlight switch is you cannot start the engine or ride the bike unless the lights are on, thus avoiding several traffic tickets.
 
Osteoderm,

I just got that same switch. What did you end up doing? I am hesitant to hook the ignition to the headlight because if you have to kill the bike while moving, you are also shutting off the headlight. I had my power cut out completely on the highway at night... scary not to be able to see where you are going.
 
sbtm said:
Osteoderm,

I just got that same switch. What did you end up doing?
Click to expand...

I wired it up using a DPDT relay as diagrammed above; relay contacts rated for 7.5A, fused appropriately, all connections soldered. If you are not 110% comfortable with this sort of "relay logic", wiring, soldering, etc., then some other more conventional killswitch is probably a better bet. Having said that, I'm happy with my own setup, and have had zero issues with the killswitch.
 
You can do the same thing using a more common and cheaper SPDT relay.

spdtkill.jpg

These relays are available at most auto supply stores for about $5.

relay.jpg
 
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sbtm said:
Osteoderm,

I just got that same switch. What did you end up doing? I am hesitant to hook the ignition to the headlight because if you have to kill the bike while moving, you are also shutting off the headlight. I had my power cut out completely on the highway at night... scary not to be able to see where you are going.
Click to expand...

Please read my post again. If you have to kill the engine at night you can push the kill switch button even with all of it's limitations.
 
pamcopete said:
You can do the same thing using a more common and cheaper SPDT relay.

spdtkill.jpg
Click to expand...

The issue with this particular KTM switch is that it only has one terminal, which goes to ground when depressed. This is the detail that required the additional complication.

I agree with Pete that, using a conventional normally-open momentary switch with two terminals, the above diagram with the common SPDT relay is better.
 
osteoderm,

Bummer. I presume that the ground is a wire and not just a contact to the handle bars? In which case it is probably used for the kill switch and the horn so you could just run the horn with a switched battery instead of ground and then connect the "ground" wire to the ignition switch.
 
Way back when, Porsche used a relay which had a 'ratchet' type mechanism in it to run the high/low beams on the 914's etc. The column switch was a momentary ground which energized the relay coil and switched the terminals back and forth with each pull of the momentary switch. So, pull lever = low beam, pull lever again = high beam, pull again = low beam, etc. This should be the same relay:

http://www.ebay.com/itm/Porsche-914...Parts_Accessories&vxp=mtr&hash=item35c2528b75

So if you go with this, if you press the kill switch you'd open the circuit to the ignition, thus cutting power. Press the switch once again, power is restored.
 
pamcopete said:
osteoderm,

Bummer. I presume that the ground is a wire and not just a contact to the handle bars? In which case it is probably used for the kill switch and the horn so you could just run the horn with a switched battery instead of ground and then connect the "ground" wire to the ignition switch.
Click to expand...

Yes, the ground is wired, and common with the horn, and I see where you're going there... In my case, I also wanted to keep the ignition and horn (and everything else) on separate fused circuits. Perhaps unnecessary, but it's just my preference to use as many discrete fused circuits as practically possible; it makes troubleshooting and future modifications a little easier for me.
 

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