Why do motorcycles have a separate engine stop switch?

I would argue that it, like an appendix, is a useless holdover. Back in the day, when magneto ignitions were used, motorcycles didn't have an ignition switch. You'd get on the thing, prime it and kick it over and it would start. When you wanted to stop the engine, you'd hold down the kill switch, grounding out the magneto, until it quit, so an engine stop switch had a function. Nowadays, when you turn the ignition key to off, it serves the same function, so there's no need for a separate engine stop switch. I'm fully aware that the MSF teaches students to use the engine stop switch to kill the engine rather than the ignition key. When you ask why, they say that it's to teach people to use it in an emergency. Um, you can't flip the ignition key in an emergency? Do cars have an engine stop switch? Of course not, so why do motorcycles?

I would further argue that engine stop switches cause way more trouble than they're worth. How much time has been wasted figuring out why the thing wouldn't start when the kill switch got accidentally bumped. How many times has the engine quit while going down the road because the switch got bumped by a rider fumbling with a glove or some such. How many times have riders run down their batteries because they stopped the engine with the kill switch and forgot to turn off the ignition?

QUIT USING THE KILL SWITCH!

Incase of a crash anyone can turn the engine off quickly without having to fumble for the Key. Most non moto people have no idea where the key switch(ignition switch) is, but they can see the bright orange switch on the handle bar. Not to mention I as a rider can shut the bike down quickly if necessary without taking my hands off the bars. Those of us who make the mistakes you mentioned only do it a couple of times and then we learn.

CARS SHOULD HAVE IDIOT SWITCHES, which automatically turn off when the driver does something stupid. ie. texting while driving.

Chucksklrst said:

Incase of a crash anyone can turn the engine off quickly without having to fumble for the Key. Most non moto people have no idea where the key switch(ignition switch) is, but they can see the bright orange switch on the handle bar.

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I think that most non-moto people have no idea that there is a kill switch and would not look at a handlebar full of switches for one. Instead, they would look for a key because that's what they're familiar with.

Not to mention I as a rider can shut the bike down quickly if necessary without taking my hands off the bars.

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In hundreds of thousands of miles of riding over the past 50 odd years, I've never had occasion to do that, nor do I know anyone who has. Besides, you can always squeeze the clutch or flip the key.

Those of us who make the mistakes you mentioned only do it a couple of times and then we learn.

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But the mistakes would not be made in the first place if the anachronistic switch weren't there. How many years of experience does it take to learn? Hey, Phil!

CARS SHOULD HAVE IDIOT SWITCHES, which automatically turn off when the driver does something stupid. ie. texting while driving.

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You got that right, brother!

bicyclist said:

CARS SHOULD HAVE IDIOT SWITCHES, which automatically turn off when the driver does something stupid. ie. texting while driving.
You got that right, brother!

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Wow - there would be a whole lot of cars parked on the interstates then. Talk about grid lock!!!!

There is a kill switch because federal law 49 CFR 571.123 Sections S5.1 which states "Each motorcycle shall be equipped with a supplemental engine stop control, located and operable as specified in Table 1." So for me, it is clearly Table 1's fault.

I think the evolution of the kill switch on Honda 4 strokes is different than you explain. I had several late 60's Honda that had ignition switches but did not have kill switches. These were fun machines with single throttle cables that were connected to carburetors that had little weak throttle return springs. It was perfect set up for an exhilarating ride accelerating from 60 mph into a 25 mph corner with a stuck throttle. A riders choices were equally exciting, but limited.

The first idea that comes to mind is to pull in the clutch. Certainly that will help regain control of your Honda beast, but are you prepared to hear an unrestrained engine liberating it's innards as rev limiters, like the kill switch, are not part of the equation yet.

Choice #2 was to reach down and manually return the carburetor. This required some pre-planning and practice runs until you had muscle memory of exactly where the carb is located. It was important to practice your emergency throttle grab with a gloved hand in your casualty training to ensure you have completely lost any sense of touch fumbling for the carb. Only a precision blind and touch-deprived grab will save your butt. As an added bonus the gloved hand aided in preventing any serious exhaust pipe burns on those high pipe scramblers models. The pipes acted as a cage for the carb and upped the difficulty factor of pulling off the hot-run-carb-grab. As tedious as the self-training sessions were they could yield good results, and better than the final choice.

The final choice is appropriately named "The final choice." Choice your line and aim between the hazards, go with the flow, an ride it. Go ahead, stomp on some brakes if your want, your fate is sealed. You may think countersteering will pull you through that curve but physics says no. Crashing was the easiest choice and proved to be the most popular.

I also had some early 70's Hondas. Somewhere between the late 60's and the early 70's Honda added kill switches in a futile attempt to make motorcycling safe. It wouldn't be long before more senseless safety needs would overcomplete the beauty of the simple beauty of 60's Honda. Things like kickstand switches, clutch switches, and the highly debated ABS all in the name of safety. Oh look, wireless throttle control. Hope it doesn't stick.

So at least for some Hondas, the kill switch was added after the ignition switch.

junglejim said:

Wow - there would be a whole lot of cars parked on the interstates then. Talk about grid lock!!!!

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That would be fine with me so long as lane-splitting is legalized first!

bicyclist said:

How many times have riders run down their batteries because they stopped the engine with the kill switch and forgot to turn off the ignition?

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Shoot, I don't even need a kill switch to do that -- I can kill the engine by lowering the sidestand while the ignition is on and then not turn the key to "off." Seems like I do it every 2-3 years. Did it yesterday, so I'm good for another 2-3 years.

I had forgotten the magneto kill switches.
I thought the kill switch was there because for a while it was popular to put the ignition keyswitch on the left side just below and to front of the fuel tank. If a bike went down on the left side the switch would be hidden under the bike and hard to access quickly. A kill switch on right handlebar would then be available.
With the location of our keys, the kill switch is just leftover extras.
But don't we have some other EU leftovers also? Position lamp?

Brad

Federal laws that took effect with the 1974 model year, mandated the standardization of switch and locations, as well as shifter location and shift patterns, clutch, throttle, brake controls, etc. Turn signals also became manditory. Prior to that shifter were sometimes on the right side or hand shifters, etc.
I would not like to see the "kill switch" go away. I have seen more than a "few" new riders freeze on the controls and crash. I have also prevented some new riders from crashing during training, by yelling as loud as I could, "KILL SWITCH, KILL SWITCH, KILL SWITCH!!!!!"
I would instruct students that MSF did not like the term "kill switch", that was easier to say and faster than engine stop switch.

Probable because I started riding motorcycles before they had kill switches but I never use the kill switch to turn off the motorcycle. I always use the ignition key. No reason other than habit.

The only way to stop my 1970 Husqvarna was what looked like a doorbell button, was the only way to stop the motor. I learned to use the kill switch on my NT, I use it mainly at gas stations. With all the farkles, tank bag, GPS, located in convenient locations while riding, it's easier to shut the bike down then reach for the key. When I have to adjust my gloves or scratch my nose, a quick stop, hit the kill switch, do what I need to do, then take off. With 40 years of riding, I'm more careful what I do while the bike is moving. I find as I get older, my reaction time is slower and concentration is important. Just my opinion, we all do our own thing. BB

dnktng said:

There is a kill switch because federal law 49 CFR 571.123 Sections S5.1 which states "Each motorcycle shall be equipped with a supplemental engine stop control, located and operable as specified in Table 1."

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Ha! There it is. It's the gummint's fault. Rise up in protest!