The Kill Switch Problem

zixaq

Elite Member
I picked up an extra kill switch/ignition housing to mess around with and, long story short, the only cost-effective way to harden the mechanism against failure is to add a shim. Otherwise, I'd recommend cleaning it out at least once a year, especially if it gets wet regularly or if you use it frequently.

I took some pictures of disassembly and thought I'd share them. I forgot to take images of the cleaned-up parts and reassembly, but I'd guess you can all figure out how to do that.



Above you can see the clamshell pulled apart initially, showing the very, very dirty insides.



Now I've removed the black plastic insert that holds the wires clamped down as well as the small brass screw that holds the kill switch in. Now comes the tricky bit:



Use a flat screwdriver to gently pry the indicated white flange back a bit, and you should be able to pop out the black plastic plate that the wires run too, revealing the contact points for the kill switch:



The contacts are pretty grody. I gave these a good scrub with toothbrush/toothpaste and hit them with a scotch-brite pad and vinegar and they now sparkle.



Getting the kill switch itself out is extremely fussy. Be careful and don't use too much force. There is a ball bearing and two small springs that you must not lose.



Eventually you'll get the switch out and can remove the little bits and pieces. The small copper plate with the two bumps is the bit that closes the circuit when the switch is in the "run" position. Clean it VERY THOROUGHLY and reassemble. If you want to modify the mechanism to make a better contact, you can insert a small shim between the spring and copper plate when reassembling. I used a small rectangle cut from a disused credit card, similar to adding a preload shim to a fork. Nothing in here really needs/wants lube, but if you'd like you can add a touch of lube to the plastic bits that rub against one another.

I was a little disappointed that I couldn't find a better solution, but I'm hoping just a thorough cleaning and the shim will make it more reliable. Those copper contacts wear down over time with frequent use and lots of vibrations. Water gets into the clamshell and causes corrosion. Eventually, the connection becomes intermittent or has some resistance, and then you will have a bad time. There are a few companies that offer small springs approximately the correct size, but I'm not sure if they're equivalent spring rates or how much extra force would be beneficial. For reference, the spring is 3.0 mm Outer Diameter, 5.6 mm Free Lenght, with ~0.2 mm wire diameter and six windings. One comparable product can be found at https://www.springsfast.com/part_detail_compression.php?part=C04-010-008.

On a tangential note, I don't need an extra switch assembly anymore, so if anyone would like a freshly cleaned and serviced, although cosmetically challenged, switch & housing, PM me and I'll ship it to you for what it cost me ($25).
 

Motogiro

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Thank you for the images! This, I'm sure we'll use, as a reference for future kill switch diagnoses.

Great job!
 

TownsendsFJR1300

2007 FZ6
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Thank you for the images! This, I'm sure we'll use, as a reference for future kill switch diagnoses.
The more I think about it, the more (if/when I have an issue with it) I'm likely to just bypass the switch(and connect inside the housing)...


Think about it.. Should you go down, the TOS will kill the engine.

When would you actually NEED to use the switch vs the key?

Just one more thing to fail over time...
 

Gary in NJ

Junior Member
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I've been riding street bikes for nearly 40 years (and dirt bikes 10 years longer than that). On a modern (post 1990) street bike I can't think of a good reason to have a secondary kill switch. Back in the "old days" when ignitions switches were typically mounted below the left side of the fuel tank I could see the value of the secondary switch; but modern bikes have a keyed switch that is readily accessible. Other than lawyers or the government requiring these switches, I see no reason to have them.
 

zixaq

Elite Member
I agree on it being unnecessary. I'm not planning on selling this bike, so I'll probably just solder a shunt across the wires once I'm sure my new state won't check it.

To give you an idea of how badly it can go wrong, here's a picture of my kill switch:



That's not debris or dirt, that's actually scoring where copper has been removed. Something caused an arc across those contacts and fried them.
 

Motogiro

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There are a few instances where the kill switch comes in handy for me. It's more of a personal issue because I'm 5'7" and sometime I find I'm in a parking situation where I'm tilted in 2 directions and I want to use the transmission the lock me in place. I need the engine off and don't want to release my grip on the bars to shut the engine off so I hit the kill switch. This only happens once or twice a year but I would still like the option.

The loss off metal on those contacts is probably due to arc and dirt on the contacts. I hardly ever use my kill switch but I know it is a habit for some. Constant use should not result in failure but I believe because of a few factors these switches tend to have a higher rate of failure.

The current passing through that switch is mainly current supplied to the ignition coils and another small current relay coil on the starter cutoff relay board. Reducing current at the kill switch contacts could be accomplished using it as a control switch for a multi pole relay. The relay would have multiple contacts thus increasing contact reliability, as well as being away from the elements adding to the reliability. The kill switch contacts would be alleviated of the higher current inductive arc from the ignition primary winding. The relay contacts could also be further protected. :)
 

TownsendsFJR1300

2007 FZ6
Site Supporter
There are a few instances where the kill switch comes in handy for me. It's more of a personal issue because I'm 5'7" and sometime I find I'm in a parking situation where I'm tilted in 2 directions and I want to use the transmission the lock me in place. I need the engine off and don't want to release my grip on the bars to shut the engine off so I hit the kill switch. This only happens once or twice a year but I would still like the option.

QUOTE]

In a case like that (rare for me), I just put the kick stand down and that safety switch kills the engine...

Also, if your on a hill, the stand should help prevent tipping over (at least on one side).

Just something to consider . :)
 

bricksrheavy

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Grime gets way to easily into the switch cluster and under the throttle tube so now I simply make it a habit to remove them and clean every once in a while.

Couple of months ago my key froze in the ignition while riding (long story full of stupidity :D ) - and since I bricked my kill switch the only way to shut the engine off was to put it in gear and put the sidestand down.

Still don't miss the kill switch, two mid corner cut-off scares were enough.
 
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