How do Kill Switches work?

Shlink · Oct 12, 2010

I understand they stop the spark plug from sparking, but I'm wondering how they do it. Does it just cause a short between the power and ground? Do kill switches do the same thing as normal switches and just complete the circuit?
I've heard the kill switches that come with most kits are garbage. If I'm going to replace it I would like to use one that toggles on/off. I plan on pedaling a lot when I get into town on sidewalks and such.
Will any normal 12volt toggle switch work?

Derks420 · Oct 12, 2010

They are considered a momentary switch, which momentarally completes the circuit and does not allow the cdi to spark.

Go to your local radio shack and you can pick up a pack of 2 for a couple bucks. Very simple to replace the garbage one that comes with the kit.

Dont use a toggle switch. those can be difficult to use in a hurry, plus a big switch sticking out of your handlebars dosent look to good.

If you get the same one I did, all you need to do is take the old switch out, but leave all the wires there.
Drill out the kill switch hole to where it is just bigger than the new kill switch, so its a nice tight fit after you rewire and tape off the connections.

This is what it will look like...
Ill post better ones tomorrow

Shlink · Oct 12, 2010

Hey, thanks for the fast reply, but I suppose a toggle switch being difficult to use and not looking good are just matters of opinion.
I would still like to use a toggle switch.
What I need to find out is if I can use a normal toggle switch as an on/off kill switch, or if I would need to buy a special type of switch. I'm not familiar with the mechanics of kill switches (if they are different than normal ones

)
Also If I can use a normal one, would I just wire it like the diagram in my first post?

bairdco · Oct 12, 2010

i've used toggles and pushbutton/momentary switches instead of the regular kit supplied switch, since i change out the crappy plastic throttles on all my bikes. any twelve volt one should work. all it basically is, is an interruption in the wiring.

i hook the white wire up to one pole on the switch, and have a ground coming off the other pole. the ground connects to the frame.

on one of my bikes, the kill switch is in the end of my lay-back seat post and wired internally through the frame. you have to reach back like you're itching your butt to kill it, but i'm used to it now, and i like having it hidden.

this picture is older, before i wired it through the frame.

2door · Oct 12, 2010

Switch ratings (voltage) is unimportant. Any switch will work. Shop around and you can find nice looking toggles, rockers and push button types. Radio Shack is one source but many good auto parts stores will also carry a line of attractive switches used for aftermarket accessories such as fog/driving lights etc.
You'll want the switch off (contacts open) for engine operation and on (contacts closed) for pedaling. Wire the switch in parallel with the blue and black wire from the magneto/CDI.
Tom

DudeZXT · Oct 12, 2010

The way these kill switches work is kind of controversial. The factory wants us to wire in a short-circuit in order to kill the spark, rather than to have a switch in series, which would open the circuit (which tends to be less stressful on electrical components)...

Shlink · Oct 12, 2010

Awesome, thanks for the help guys. You all gave me exactly the answers I need.

DudeZXT said:
The way these kill switches work is kind of controversial. The factory wants us to wire in a short-circuit in order to kill the spark, rather than to have a switch in series, which would open the circuit (which tends to be less stressful on electrical components)...

Thats what I thought DudeZXT thanks. I bet wiring the switch in series could potentially burn out the switch and would probably weaken the spark.

DudeZXT · Oct 13, 2010

If you were to wire the supplied switch in series, you would have to hold the button in all the time in order to complete the circuit. My suggestion would be to get a heavier duty normally-closed switch with matched wire gauge to that of the blue & black wires that go to the CDI. It seems amazing to me how they managed the circuit with the puny wires that feed the CDI, in the first place...

scotto- · Oct 13, 2010

Mine works well, thanks. Doesn't yours? I like rockers and toggles.....especially lit ones, that light up the night.

If you have a 2-stroke, just dump the clutch.....you don't need a kill switch to kill the motor.

Dave31 · Oct 14, 2010

Here is the toggle on the J-dog, less then $2 at the local auto parts store.

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How do Kill Switches work?

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