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Norm's 2 stroke repair center Having problems with your 2 stroke engine? Just ask Norm, he loves to tinker and troubleshoot engines


Kill switch wiring

Having problems with your 2 stroke engine? Just ask Norm, he loves to tinker and troubleshoot engines


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  #1  
Old 05-11-2009, 11:40 AM
rslavicek rslavicek is offline
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Default Kill switch wiring

I'm finishing up my first build and as usual confused buy the chinese-english translations. My instructions tell me to hook up the white wire coming off the engine to the yellow wire on the kill switch but make no mention of the green wire coming from the kill switch. My best guess is that it's a ground and needs to be connected to the engine, but someone put a plastic sleve over it, which got me wondering if I should just not attach it. Would appreciate any help you can come up with. Worst case I will go with my gut and if it blows tha magneto then I have another project.

2Door has the way I do it to wire up the engine. you can get by with just one wire to the engines blue cdi wire and one to a ground(frame or engine or the black wire). The black wire from the engine to the cdi is a ground. Some kill switches only have one wire. 2 wire kill switches either wire from the kill switch to the blue on the cdi and one to a frame ground will work. I leave the white wire for a light. if your not using a light cap off the wire. Best bet is use the diagram the 2Door has.
Norman

Last edited by Norman; 05-11-2009 at 09:55 PM.
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Old 05-11-2009, 01:15 PM
Echotraveler Echotraveler is offline
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Default Re: Kill switch wiring

ok heres how i was told/did/do

theres 3 wires coming from the motor
*the white is only for the light
and other 2 (this to go to the spark)


what do i do with the 2 wires coming from the kill switch

its so simple, one could get confused...one of the cables of the "kill switch" gos to one "wire of the spark" and the other "kill switch wire" to the other "spark wire".


whats difficult to explane/understand, is that you still connect the "motor wires" to the cdi and also the "killswitch wires".

you end up with 2 x 3wire union
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Old 05-11-2009, 01:21 PM
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2door 2door is offline
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Default Re: Kill switch wiring

Try it this way. It will work just fine. Promise.
Tom
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Old 05-11-2009, 01:56 PM
rslavicek rslavicek is offline
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Default Re: Kill switch wiring

Thanks all. I will go ahead and follow your advice. Has anyone found a way to shorten the throttle cable. Mine seems to work but it sticke out over the front wheel and looks sloppy. I'm taking it slow, I've been waiting for a sprocket adapter and making modifications as I go.
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Old 05-11-2009, 03:32 PM
Echotraveler Echotraveler is offline
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Default Re: Kill switch wiring

the long throtle cable would be more aesthetic...some tight wrap should at least let you fine tune the MB...

to shorten it you would need the end caps for the cable....maybe someone can shime in on that.
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Old 05-11-2009, 09:35 PM
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Norman Norman is offline
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Default Re: Kill switch wiring

Yes you can shorten the throttle cable.
http://motorbicycling.com/f39/motori...build-302.html
permalink 17 tells how to make the throttle cable end.
If you run into a snag let me know.
Norman

Last edited by Norman; 05-11-2009 at 09:56 PM.
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Old 05-12-2009, 12:33 PM
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Default Re: Kill switch wiring

I have a 2 wire kill switch and I am having trouble understanding how this works.

The diagram shows a splice in the engine ignition that will stop the current and stall the engine. I get that one.

The other way to do it is the way mine is instructing me to do it, by attaching the yellow wire to the white engine wire and ground the green. I did this and it failed. I believe the ground was poorly grounded and I will try again. If it does not work I am worried I cannot splice the black and blue wires, as they are very short. I would have to cut off the little connector bits installed and get some three way connectors, but I would also have to move my cdi closer (very close) to my muffler.

I also do not understand how this ground system works. If the switch is open and pushing it closes it, then how is it not constantly grounding itself? It seems like this switch has to be a closed switch and opening it sends the current into the frame to short the magneto. If this is true I don't see how the alternate wiring system can work. would I need a new switch?

please help me on this, I don't want my second ride to be the unstoppable top speed death roll the last one was. I think I figured out the carb now, thanks to the help of this forum, but I would like to be safer next time. thank god for brakes.
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Old 05-12-2009, 01:03 PM
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2door 2door is offline
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Default Re: Kill switch wiring

Let me see if I can make this simple and understandable for you. The kill switch is a simple, normally open contact, called a momentary switch. When you push it it connects the two wires connected to it together. The black wire from your engine is a ground. It is connected directly to the engine case inside the magneto cover. The blue wire carries a pulsed current to the CDI (coil) and the black wire completes that circuit. By connecting your wiring as in the diagram I posted above what you do is ground out the blue wire when you push the kill button. The same thing can be accomplished by grounding the white wire to the engine or bike frame if the engine is attached to it in such a way as to allow an electrical connection (no paint, rust, rubber etc). The white wire however is provided as a power source for a small light bulb (headlight/tailight). If you elect to use the white wire to one of the kill switch wires then the other kill switch wire will need to be attached to preferably the engine case or the bike frame if there is good metal to metal contact. I hope this clears the wiring issue up for you. If you have doubts about my advice remove the magneto cover and look at the wiring for yourself.
Tom
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Last edited by 2door; 05-19-2009 at 11:13 AM.
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Old 05-16-2009, 11:27 AM
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Default Re: Kill switch wiring

I have no doubts 2door, and that was a lovely explanation. thank you.
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Old 09-07-2010, 10:32 PM
bikenerd bikenerd is offline
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Default Re: Kill switch wiring

I hope to revive this old thread. I hooked up my kill switch per instructions, black and blue motor to corresponding black and blue CDI wires, white motor to red/yellow kill switch wire, green kill switch wire to ground on frame. First ten hours of operation everything worked perfectly. Last two hours of operation the kill switch became sluggish, taking 10 to 15 seconds to kill the engine as it slowly lost rpms. Then it wouldn't run at all unless I keep the kill switch depressed which causes it to run just fine. My ohm meter says the kill switch is still operating correctly as a temporary closed switch, infinitie resistance when untouched and zero resistance when depressed. I tried various combinations of switching connections but the only one that works is leaving motor and cdi hooked up black/black and blue/blue and grounding the white wire. I don't understand what's changed or what I should do about it. I suppose I could replace the kill switch with a temporary open switch but doing things without understanding what's happening makes me uneasy. Any ideas?
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