How to make a kill switch?

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Agreen

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Feb 10, 2013
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For something non-kit? I wire the kit's switch (a simple normally-open momentary pushbutton) to where it will short the primary windings (blue and black wires) together.
 

crassius

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Sep 30, 2012
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I bought some 99cent bicycle horn buttons years ago - I run the single wire it has to ignition wire & pressing the button grounds that wire to the handlebars.

don't know if those buttons are still around, but back in the 60s I used a small piece of hacksaw blade with a wire soldered to it wrap a piece of old inner tube on bars put blade on inner tube, wrap more inner tube on top & hold with hose clamp - push the end of the blade against bar to kill it.
 

curtisfox

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Dec 29, 2008
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You can get a limit switch and put it any were on the cable or brake siston, i got some from garden tractors. They use them for stop switches like on the seats so when you get off it stops the motor.Also used in RV's. Radio shack maybe.............Curt
 

Trey

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Jan 17, 2013
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Where cattle outnumber people 3 to 1.
jazz2561- Think about anything with a small engine on it; our bikes, lawnmowers, water pumps, generators, fluid sprayers, go karts etc etc. They almost always have a switch. Check the intraweb for parts related to any of these things you may think of. There are so many variations of mounting types, materiels, colors, sizes, styles etc.
I wish I could be more specific, but there are way too many choices. I would say that you could use almost anything that interrupts the circuit, take for example crassius' idea from the 60s- that is AWESOME!

Good luck!

Thank you crassius.
 

2door

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Whatever you decide to use and how you wire it, make sure the kill switch is where you can get to it without taking your hands off the handlebars or reaching down with one hand to find it.

Kill switches are considered a safety device. It should be easily accessable if an emergency situation happens. Fumbling down under the seat or someplace equally hard to reach is no place for a device that shuts down the engine in an emergency.

Tom
 

dtv5403

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I would think if the engine has a kill wire coming off the ignition (most do?) Then taking a kit switch and hooking one wire to the kill wire and the other wire from the switch to ground should do it?
 

crassius

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not really, what most have is a blue ignition wire - when you short this to ground the motor dies - a lot of switches can do this, but it is important that it doesn't accidentally short because of loose springs or something
 

dtv5403

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Been a little while since I've been around the kit engines, all my friends used to use a white wire coming off the mag coil as the kill wire. Seemed to work fine for them. The point is that there is always some sort of wire that is somehow connected to the ignition system that can be ground out to kill the engine.
 

dtv5403

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That doesn't change my answer. If there is a kill wire coming off the ignition (be the only wire coming off the ignition if there is one, don't get no simpler than that), he can still use a kit killswitch and wire one wire to the kill wire and the other wire to ground.
 

crassius

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discussions on boards over many years suggest that any use of the white wire may damage the ignition
 

2door

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Jazz,
Could you provide a photo of your magneto? Other than the high voltage lead, (spark plug wire) are there any other wires coming from the magneto?

Many older Briggs engines relied on a metal strap that pressed against the spark plug and grounded it. They didn't have any 'igntion wires' that you can splice into.

Tom
 

curtisfox

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There is a small black wire that comes out of the coil that goes to a kill switch,it depends on the model. a lot of bigger 5---8 hp the wire went to a insulated screw post that a kill wire form there to a ignition switch. Like @ door said need a picture.............Curt
 

fatdaddy

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May 4, 2011
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Been a little while since I've been around the kit engines, all my friends used to use a white wire coming off the mag coil as the kill wire. Seemed to work fine for them. The point is that there is always some sort of wire that is somehow connected to the ignition system that can be ground out to kill the engine.
NEVER use the white wire for anything. just cut it off or cap it. using it for the kill switch will shorten coil life. Any momentary on switch will work for a kill switch, (like a horn button.) One wire to black and the other to the blue. HIT THE SWITCH and the engine will die without harming the coil. The new style coils don't even have a white wire.
fatdaddy.usflg
 

fatdaddy

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Jazz,
Could you provide a photo of your magneto? Other than the high voltage lead, (spark plug wire) are there any other wires coming from the magneto?

Many older Briggs engines relied on a metal strap that pressed against the spark plug and grounded it. They didn't have any 'igntion wires' that you can splice into.

Tom
yer telling your age Tom. that kill strap hasn't been used since I was a kid.
 

2door

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yer telling your age Tom. that kill strap hasn't been used since I was a kid.
But it would still work today. That's the beauty of 'old things'. They work. :)

And, we don't know the vintage of the OP's engine. A Briggs flathead could be older than me, and that's old.

Tom