Kill switch origin?

[Motu]

And don't get him started on left side gear change

Yes,came in as a law,rather than just being there,with the left foot change,right hand throttle,orange side reflectors etc.Courtesy of the country with freedom of choice.

[rocketman1]

Mentioned this previously but to say that some times bikes especially 2 strokes can decide to do their own thing that is rev full revs all by themselves ie reigniting and drawing petrol all by themselves - no throttle.
I have experienced it and its scary thing, nothing you can do to stop them, even the kill switch doesn't work sometimes.
There is quite a bit written out this phenomemon, used to happen in world war 2 aircraft also.
I guess then the kill switch would be your only saviour

[Motu]

rev full revs all by themselves ie reigniting and drawing petrol all by themselves - no throttle.

They need air from somewhere...I think you will find a jammed slide here.In such a case with 2 strokes - the decrompressor was very handy...at the expense of a wild rear wheel slide.

[slofox]

Your what didn't? Make,model and year please.

1953 Ariel "Red Hunter" ...350cc.

[Ixion]

Runter was Lucas Magdyno wasn't it? They had an earthing terminal (U on attached diagram). Take wire to pushybutton on handlebars or in nacelle.

[Oscar]

Mentioned this previously but to say that some times bikes especially 2 strokes can decide to do their own thing that is rev full revs all by themselves ie reigniting and drawing petrol all by themselves - no throttle.
I have experienced it and its scary thing, nothing you can do to stop them, even the kill switch doesn't work sometimes.
There is quite a bit written out this phenomemon, used to happen in world war 2 aircraft also.
I guess then the kill switch would be your only saviour

Two strokes will also run backwards...and if hot enough will continue to run with no ignition...my DT250 turned into a diesel once...

[BMWST?]

when did the kill switch as we know it today make its appearance.i dont think my cl175 or dt3 had a kill switch,my cb500 might have and my 1978 sr500E definetly did

some two strokes can run backwards,and i think 4s radial engines can too

[Ixion]

Two strokes will also run backwards...and if hot enough will continue to run with no ignition...my DT250 turned into a diesel once...

Flooding crab and worn crank seals.

[Oscar]

Flooding crab and worn crank seals.

Nah, it was stuck throttle cable - the thing hit a squillion revs on test starting after some minor work, and unfortunately the minor work involved disconnecting the ignition key (smart eh?). When the throttle jammed wide open and the kill switch failed to work, I grabbed the spark lead and yanked it off (my right arm refused to work for about an hour after and my shoulder felt like someone hit it with a sledgehammer), whilst yelling at my mate Dave to turn the gas off.

More surprising than the 50 megawatt jolt I had just received was the fact that the pig kept running, sans spark plug lead, and at red line.

Dave took the initiative at this point and kicked the thing into gear, whereupon it spun up a brand new knobblie on the nice concrete floor in my Dads garage and after two or three seconds launched itself into the opposite wall, finally spluttering to a halt as it ran out of gas...there was a momentary silence and Dave collapsed into hysterical laughter.

[Motu]

That's when you need a decompressor.

I tossed my TM400 into a turn on the dirt track wound out in 3rd gear....and the 38mm Blue Magnum jammed wide open.That's when I remembered I had disconnected the kill switch,and never bothered to fix it.So I ''layed it down'',as you do on a speedway track,and rag dolled down the track,the bike cartwheeling with the throttle wide open.When I got to the bike to shut it down....I remembered I had fitted a decompressor.Duh,the things you forget in the heat of the moment.

[rocketman1]

Nah, it was stuck throttle cable - the thing hit a squillion revs on test starting after some minor work, and unfortunately the minor work involved disconnecting the ignition key (smart eh?). When the throttle jammed wide open and the kill switch failed to work, I grabbed the spark lead and yanked it off (my right arm refused to work for about an hour after and my shoulder felt like someone hit it with a sledgehammer), whilst yelling at my mate Dave to turn the gas off.

More surprising than the 50 megawatt jolt I had just received was the fact that the pig kept running, sans spark plug lead, and at red line.

Dave took the initiative at this point and kicked the thing into gear, whereupon it spun up a brand new knobblie on the nice concrete floor in my Dads garage and after two or three seconds launched itself into the opposite wall, finally spluttering to a halt as it ran out of gas...there was a momentary silence and Dave collapsed into hysterical laughter.

Hey I would have paid to see that, the throttle does have to stick open for two stroke to do that, they can suck air from under the float bowl if the float is set incorrectly. I am proof of it... kehin flatside carbys

[pete376403]

Re dating kill switches - my 72 kawasaki Bighorn 350 didn't have a k/s as standard, although the wiring to support one was in the loom. When I took the indicators off (as everyone did with dirt bikes in the 70s) I used the indicator switch as a k/s (run in the centre and off either side)

As for two stroke runaway - my IT400 (which DID have a k/s) did this when the barrel base bolts came loose and it started sucking air in there. It promptly spat me off, by the time I got to it it was screaming its head off. K/s didn't do anything, trying to jam the rear brake on didn't do anything (because the brakes were useless anyway), turned the fuel off and waited for it to stop. That was a very long minute or so. After it stopped, got out a 12mm spanner, tightened up the bolts and carried on with the ride. Just had to keep tightening the bolts every time I had to stop to open a gate or something. When we got to a town, bought a cheap-ass (Motogard) 3/8" socket set at a gas station, pulled the head off and tightened the bolts properly, put the head back on. Air cooled two strokes are brilliant, almost impossible to break and dead simple to fix when you do break them.

[mctshirt]

Flooding crab and worn crank seals.

Are these like hermit crabs and fur seals at Ngawi?

[one fast tl1ooo]

Where did the kill switch come from?

I'm thinking long ago something bad must have happened that made the appearance of kill switches on bikes a standard item.

Back in the old days bikes needed to be kick started - so perhaps they needed an off button just too

[Mystic13]

The kill switch like many motorycle features was invented by BMW.

BMW were the first to put telescopic forks on motorcycles and over time the world followed.

BMW were the first to mass produce the Hossack front suspension and with time hopefully that will become the standard. Lighter, cheaper and better than forks.

BMW led the way with ABS and traction control in consumer bikes.

BMW installed the kill switch in their range of bikes with the belief that it was necessary at times to kill the motor and the kill switch should be easily reached. Motorcycles today and roads today are much different to those in the days when the switch was first created. When a motorcycle crashes it does one other thing that cars don't and that is it is always on it's side (mostly - a friend of mine put his GS850 into a clay bank, he flew forward, hit the bank and bounced back onto the seat before toppling to the side and ground while his bike stayed upright). So a bike on it's side can leak petrol in which case being able to quickly kill the engine is a necessity. A standardise kill switch position is useful. In the event the rider is onto it they can also kill the engine as the bike slides.

Today pretty much every manufacturer has followed suit.