View Full Version : Wiring in a "normally open" tether kill switch
hal20308
8th October 2019, 09:31
In preparation for Greymouth, I have a tether kill switch that's designed to close the switch to ground (normally open circuit). Much trawling on the web seems to indicate connecting this to the coil feed wire from the CDI to kill the engine is a bad idea (although all the pit bike boys and gals seem to do it this way). My old XR200 grounded one of the stator wires, but on an FXR, which one? Anybody wired one of these in to an FXR running standard electrics minus the battery? Might be easier to get hold of a "normally closed" tether switch and wire it in series to the kill switch I already have........
Thanks muchly - Nick
Drew
8th October 2019, 19:04
I've always used normally closed versions. Old school dirt bikes used normally open, I doubt they do any more.
mr bucketracer
9th October 2019, 07:04
one way is earthing the coil wire or the other type of switch is braking the - or+ if total loss
hal20308
10th October 2019, 09:30
one way is earthing the coil wire or the other type of switch is braking the - or+ if total loss
Thanks All - picked up a good quality "normally closed" full switch kit yesterday from TSS in the Hutt. They have both types on the shelf if anybody down here near Welly needs one.
Cheers
Nick
GazzaH
10th October 2019, 18:45
Normally closed kill switches tend to fail-safe: if the wiring to the switch fails open, or the switch corrodes or falls apart, the bike cuts out and that is usually safe ... but switch contacts can get welded shut by passing excess current or high voltage spikes (such as on an ignition system/coil's output, obviously, but also possibly on the input side), and the wiring can short out (so make sure the connections are secure e.g. soldered or properly crimped, and well insulated).
Normally open kill switches tend to fail unsafe: broken switches or wires, loose contacts, corrosion or dirt in the switch may prevent it cutting the bike when it is needed ... but shorts in the wiring are likely to cut the bike and that is usually safe. Annoying but safe. Usually.
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