Why Do Motorcycles Have a Kill Switch?

While many modern motorcycles have a kill switch, some people say they haven’t used one, and some don’t know what a kill switch is for. Although you rarely use a kill switch, if you don’t understand its existence and purpose, it might be very damaging in an unlikely event.

So, why do motorcycles have a kill switch? To put it simply, the kill switch is a protection mechanism that turns off the motorcycle as quickly and easily as possible in an emergency. This might also be referred to as an EPO, which stands for emergency power off, particularly on motorcycles.

There are arrow marks next to or above and below the kill switch indicating whether the circuit is engaged (the engine can be started), and a cross indicates that it has disengaged (the engine is off and cannot be started).

These marks are the same for all manufacturers and models. Some aftermarket kill switches are marked as “ON” and “OFF” instead.

How the Motorcycle Kill Switch Works

The kill switch shuts off the ignition system, including the ignition coil and fuel injection system, to shut off the engine.

As a result, the engine can be slowly stopped even while driving if you press the kill switch while driving. The engine brake will also be applied if the spark plug stops firing while the gear is engaged. Thus, a rapid deceleration occurs first, and the engine slows down after some time.

  1. A motorcycle’s kill switch is a safety precaution that helps prevent the motorcycle from accidentally getting started
  2. The kill switch can disable the vehicle’s ignition and electric starter
  3. A motorcycle’s kill switch is a safety precaution that helps prevent the motorcycle from accidentally getting started
  4. The kill switch can disable the vehicle’s ignition and electric starter.
  5. The kill switch is located in the right side of the handle bar.
  6. It is a spring loaded switch that is pressed down to engage the ignition and starter
  7. It is a good practice to turn off the motorcycle’s kill switch when parking

Role of Kill Switch on a Motorcycle

On a motorcycle, the kill switch stops the engine, but it is rarely used. Sometimes people accidentally press it while driving, and the engine stops in the middle of the road, but it was originally intended for emergencies only.

Prevention of secondary damage in the event of a fall

When you fall on a motorcycle, the accelerator may not return until you use the kill switch. When the bike falls to the right, the accelerator often does not return, which can be caused by a loose accelerator grip or an open accelerator caught in an obstacle. You don’t want the engine running in case there’s a gas or oil leaking from motorcycle crash.

After a fall, the engine may get caught in the chain or tires, the accelerator may rotate and be dragged by the motorcycle, and it may hit passersby, which can be extremely dangerous.

In addition, if you fall, the wheels will float off the ground. Open the accelerator even a little, and the rear wheels and chain will rotate at high speeds, which is extremely dangerous.

Stopping the engine with the kill switch will prevent these dangers.

Broken throttle wire

When the throttle wire breaks, the kill switch should be used.

A motorcycle normally has two throttle wires, one on the “pull side” and the other on the “return side”. The throttle valve can be closed using the return wire if the carburetor freezes.

The accelerator operation will not work, though, if the return wire breaks or freezes, so you cannot stop the engine by turning the key.

In such cases, the kill switch is useful.

Symptoms of a Faulty Motorcycle Kill Switch

Most of the time, you won’t notice if a kill switch breaks because you don’t use it frequently. However, if you leave it the way it is, you will not be able to use it in the unlikely event, so be careful not to miss these signs.

Idling becomes unstable

Initially, idling becomes unstable if the kill switch fails.
A corroded kill switch will lose its conductivity, resulting in a decrease of voltage and current to the ignition coil, as well as a reduction of the voltage that boosts the coil. As a result, sparks are less likely to fly, resulting in a lower combustion efficiency.

As there are several other issues that can contribute to idling instability, this is not a definitive sign, but it is a good idea to keep an eye out for.

The engine will not start

With the kill switch continuing to corrode, the conductivity is now completely lost, thus the engine will not start. Furthermore, since the kill switch is connected to the engine’s ignition system, if something goes wrong, it will affect the engine.

So even if you think something is wrong with the engine, suspect a malfunctioning kill switch.

How to Repair or Replace a Motorcycle Kill Switch

Kill switches need to be replaced or repaired if they break. Since the kill switch itself isn’t that expensive, if you want to make it easy, it’s better to replace it than to repair it.

Alternatively, you can replace the kill switch yourself if you don’t want to pay wages. It is relatively simple to replace, so even people who are not so knowledgeable can do it.

Note: When in doubt, contact a motorcycle mechanic. Your motorcycle dealer can also check and replace your kill switch.

  • Check the kill switch wiring
  • Remove the kill switch coupler
  • Remove the kill switch
  • Wire a new kill switch
  • Attach a new kill switch to the handle
  • Operation check

Follow the wiring from the kill switch to remove the coupler. If it is attached with a claw, you can remove it while pressing the claw. Alternatively, if it is stuck, pull it out while shaking it up, down, left and right, and take out the screw at the bottom of the kill switch.

The new kill switch needs to be wired after all the kill switches are removed. To complete the process, attach the switch to the handle part, then pass the wiring on the coupler side in place, and finally attach the coupler.

The kill switch may not work properly if the screws are not properly tightened or the coupler is not firmly installed. Be careful.


When things go wrong with the throttle wire or when it falls, the kill switch becomes unusable. Using the kill switch can also significantly reduce the risk of accidents and injuries, so make sure you know how to use it and its purpose.

Faulty kill switch is hard to diagnose because the kill switch is rarely used. There are no symptoms of failure, so check the operation regularly, and if a problem is discovered, repair or replace it immediately.

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