When Should You Change Motorcycle Spark Plugs?

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Just like cars, motorcycles also have spark plugs. These plugs have one function: ignite the fuel to turn it into energy. This energy is what allows the motorcycle to run.

Like most engine parts, spark plugs can be used only for a limited time before they need to be replaced. Periodic replacement of spark plugs is important because the engine may not perform well if worn out.

As for the duration after which spark plugs should be replaced, you should not go any longer than 10000 miles with the same ones.

The replacement may need to be done early if the plugs have been exposed to the elements for a lot of time. That brings us to the main purpose of this article.

Although when to change motorcycle spark plugs has been answered, there is more information regarding the topic that one must know.

It is recommended to read this article in its entirety, so you don’t miss out on any vital information. So, without any further ado, let’s get straight into it.

How Long Are Motorcycle Spark Plugs Good For?

Let's learn how long do motorcycle spark plugs last

This is perhaps the most important section of the entire article. Spark plugs have a maximum lifespan of 10,000 miles.

If they are used for longer, then you can expect serious failure. Even the 10,000-mile figure is for extreme cases only.

It is recommended to check the condition of the spark plugs every 5000 miles to make sure they are performing up to the mark.

If they are not, and there is erosion, which will be discussed later in this article, you should get the plugs replaced without any delay.

Indicators Of Worn Out Spark Plugs

This section will focus on how to identify a bad spark plug. If you see any of these indicators, you should know that the spark plugs need to be replaced. Let’s get started.

  • The first thing you need to check is the color of the insulator that is present in the middle of the spark plug. If it is good, it should have a color that resembles a light to medium tan. In case of a bad spark plug, the color will not match, which means a replacement is imminent.
  • The electrodes cannot be missed when inspecting the spark plugs. You should check for erosion. Erosion is an irremovable deposit on the top of the electrode. If it is present, the spark plug may not perform to its full potential. This happens due to a variety of reasons.
  • There can be other deposits on the spark plug too. The most common one is carbon, which can easily be identified. Carbon prevents the creation of a proper spark, which may result in degraded engine performance.
    Carbon deposits on spark plugs cannot be cleaned or cleared. The only solution is to replace them entirely.

It must be noted that these issues can occur before the spark plugs have been used for 10000 miles. This can be due to a variety of factors. That is why it is recommended to check them every 5000 miles.

Why Do Spark Plugs Need To Be Replaced?

This is a question that many people want to know the answer to. What would happen if the spark plugs were never replaced? Well, in layman’s terms, you can expect a lot of problems if you don’t think replacing them is important.

As spark plugs make it possible for a motorcycle to run, with them performing poorly, you can expect poor performance too.

When they have just only started to go bad, you can expect issues such as high fuel consumption, poor acceleration and performance, and even production of more toxic gases.

So, How Does This Happen? Let’s Discuss That

  • As there is a demand and supply process in the engine, if enough fuel is not ignited, the engine will demand more fuel to keep running. This will result in poor fuel efficiency as more and more fuel is being consumed. Before you ask, yes, the difference is quite dramatic.
  • As for performance, because the combustion process is incomplete, there will not be enough energy to meet the engine’s demand.
    This will result in poor performance. Some common symptoms of bad spark plugs include delay in acceleration and rough idling. These symptoms indicate that a spark plug replacement needs to be done.
  • Finally, coming in last place is the production of toxic exhaust gases. Failing spark plugs prevent the combustion process from taking place completely.
    This means that gases such as carbon monoxide are produced, which is dangerous to inhale. It also harms the environment, which is something you should consider too.

Checking And Replacing The Motorcycle Spark Plugs

So, what can be done to check and replace the spark plugs on a motorcycle? Well, several steps need to be followed.

Although I will be listing down the steps, watching a few videos on YouTube, especially those that feature your same motorcycle model, is recommended.

Visual representations are the best, and they can help you save labor costs that workshops charge.

6 Steps For Removing A Spark Plug

  1. First, disconnect the spark plug cap from the spark plug. This is fairly simple, and all you need to do is pull back with a little bit of force.
  2. It is recommended not to do this at an angle because the cap’s inside may get distorted, which will prevent it from being seated back on.
  3. The next step is to clean the spark plug base. You may be wondering if this is an important thing. Well, it is. It is necessary because the debris can fall into the spark plug hole if it is not done. You don’t want that. It is recommended to use an air gun, as it will create enough pressure to dislodge all dust and debris.
  4. Next up is the most important part of removing the spark plug. Now, you do need a spark plug wrench for this procedure. If you don’t have one, then there is a good chance that you have a torque wrench at home.
  5. All you need to do is get a spark plug socket from the nearby store, and you will be good to go. After placing the socket on the plug, you need to turn counterclockwise. This is a simple unscrewing procedure.
  6. If the plug is too tight, you should not apply too much force. It will result in the plug shattering, causing additional problems. You should use any type of oil to loosen it up.

Now that you have removed the spark plug, you can check for all of the mentioned indicators in the article.

To recap, they inspect the electrodes, check the color of the porcelain insulator, and deposit formation. If anyone is present, then that spark plug should not go back into your motorcycle’s engine.

If you don’t want to change the spark plugs, and you have a probable reason, such as the deposit of erosion not being too worse, there is one more thing that you need to check before you continue using it.

You should check for the spark plug gap, which is a tiny gap between the side electrode and the washer. This can be done by using a wire-type feeler gauge.

The maximum it should be is around 0.8 and 0.9mm. If it is, then you can continue using the spark plug.

2 Steps For Installing A Spark Plug

  1. The first thing you need to do is to thread the spark plug. This will ensure that the threading remains intact, and it will not cause any issues the next time you need to replace it.
  2. The next step is to screw the spark plug back in. This is a simple process. You need to make sure that you don’t over-tighten it. After you have seated and screwed the new spark plug back in, all you need to do is connect the spark plug cap back, and you should be good to go.

3 Types Of Motorcycle Spark Plugs To Choose

In this final section of the article, we will be looking at the type of spark plug that is most suitable for you. Yes, there are different types, so you need to know which one is better for you.

The types that are available on the market are:

  • Copper Spark Plus
  • Platinum Spark Plugs
  • Iridium Spark Plugs

Copper spark plugs are the most common ones. They are inexpensive and are suitable for normal on-road use.

If you like to take things up a notch, then platinum one will better suit you. Platinum spark plugs can handle higher temperatures, a common cause for motorcycles kept at high RPMs.

If you use your motorcycle for racing, it is recommended to use iridium spark plugs. They are the most durable out of them all and the longest-performing ones. The spark plugs you install should all be from the same brand.

Regardless of the spark plug you choose, you should replace all of them unless you look for unreliable performance due to mismatched hardware.


I hope this article helped enlighten you and clear up some confusion. If you were looking for an article that would provide you with all the required information for when to change motorcycle spark plugs, then you will not find a more detailed one out there.

Everything has been covered, from how to change them to checking for issues. In conclusion, changing motorcycle spark plugs is just as important as changing the oil after being driven for a certain number of miles.

If you don’t do so, you can expect poor engine performance, affecting its lifespan. So, you should never delay spark plug replacement.

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