Motorcycle Spark Plugs Lifespan: How Often Should You Change?

Motorcycle Spark Plugs Lifespan: How Often Should You Change?

Spark plugs are important engine components used to ignite the compressed air-fuel mixture in the combustion chamber.

Their periodic maintenance and replacement with new spark plugs is essential for the engine to perform.

A motorcycle spark plug usually have a lifespan of 10,000 miles (16,000 kilometres). Exceptions exist with few spark plugs built to last much longer.

So, when do you replace the spark plugs in the motorcycle? The spark plugs in the motorcycle should be replaced every 8000 miles to 10,000 miles (13,000 to 16,000 kilometres). In addition, if the color of insulator is distinctly different from tan, or the electrodes have eroded, or there are excess carbon deposits, then the spark plug needs to be replaced in these cases as well.

Let us discuss in detail on how often should you change the spark plugs, how often should you check and clean the plugs, why you should check them and the steps to check or replace the spark plug.

How Often Should You Change The Spark Plugs

The spark plugs in the motorcycle should be replaced every 8000 miles to 10,000 miles (13,000 to 16,000 kilometres).

In addition, the spark plugs need to be checked every 4000 to 5000 miles (6500 to 8000 kilometres) traveled.

Most spark plugs usually have a lifespan of 10,000 miles. Few motorcycle spark plugs are designed to last longer and might have a lifespan as high as 30,000 miles. However, such spark plugs are more exceptions than the norm.

Also, when checking the spark plugs, if they are not in condition, you need to replace the spark plug.

Here are the indicators of when to replace the spark plug.

  • The color of the porcelain insulator around the center electrode of the spark plug should be a medium to light tan. If the spark plug is showing a distinctly different color, the spark plug should be replaced.
  • If a spark plug shows signs of erosion on the electrodes, it should be replaced.
  • Any excessive amounts of carbon or other deposits, the spark plug should be replaced.

These conditions when the spark plug is not at its peak working condition are also an indicator for replacement even if they have not reached the 10,000 miles mark.

Checking The Spark Plugs

The spark plugs are important engine components, which should be checked and inspected periodically along with replacing them once their life is over.

Since heat and deposits will cause the spark plugs to slowly erode, they should be removed and checked in accordance with the periodic maintenance recommended by the owner manual.

Most motorcycle manufacturers recommend a periodic check of spark plugs every 4000 to 5000 miles.

Better yet, if you can inspect the spark plugs every time you take your motorcycle for servicing, the spark plugs would be maintained in a good working condition over the long term.

Why Spark Plug Needs To Be Checked And Replaced

Spark plugs can be subjected to deposit formations. If there are deposits formed on the spark plug layer, then it would be difficult for the plug to ignite the engine. The deposits block the spark plug to generate spark in the combustion chamber.

That’s why it is vital for motorcycle maintenance that spark plugs should be free from any form of deposits.

Ensuring your spark plug is in a healthy condition goes a long way in improving and maintaining the mileage for your bike a long way.

Because spark plugs are essential for ignition in motorcycle engines, keeping them in a good condition is important for fuel combustion. If spark plug is not working fine, there will be lots of unburnt fuel coming out of the engine. As a result, there will be lots of fuel wastage which eventually will result in reduced mileage.

A masked spark plug with excessive carbon deposits will not ignite the fuel properly in each combustion cycles. As a result, there will be uneven acceleration in the motorcycle along with the wastage of fuel.

The mileage and fuel efficiency of the motorcycle will go down drastically as well.

That’s why it is important to clean up and maintain the spark plug periodically or every time you go for your motorcycle servicing. A good spark plug will provide a far better mileage when compared to a spark plug plagued with carbon deposits.

Steps To Check/Replace The Spark Plug

For checking, cleaning or replacing the spark plugs in your motorcycle, here is a detailed step-by-step procedure you can follow to ensure a smooth checking or replacing of the spark plugs.

Step #1: Disconnect the spark plug cap from the spark plug.

Step #2: Clean any dirt from around the spark plug base.

Step #3: Remove the spark plug using a suitable spark plug wrench.

Step #4: Inspect the electrodes and center porcelain for deposits, erosion or carbon fouling.

If the erosion of the electrodes is heavy, or there is an excess amount of carbon deposits, then you need to replace the plug.

If you are replacing the spark plug, then skip the next few steps and directly jump to step #7.

If the erosion is not too high or the deposits are minimum, clean the carbon fouled or wet fouled spark plug with a plug cleaner. You can also use a wire brush if you don’t have a plug cleaner.

Step #5: Check the spark plug gap using a wire type feeler gauge.

The spark plug gap should fall within the tolerance limits specified by the manufacturer. The ideal gap recommendation can be found in the bike owner’s manual.

The typical spark plug gap should be between 0.03 – 0.04 inches (0.8 – 0.9 mm). However, you need to check the owner manual of your motorcycle model since the ideal gap can vary slightly from manufacturer to manufacturer.

Step #6: Make sure the plug washer is in good condition.

Ensure the plug washer is not damaged. In case it is damaged, you need to replace the spark plug entirely.

Step #7: Install the spark plug.

With the plug washer attached, thread the spark plug in by hand to prevent cross-threading.

Step #8: Tighten the spark plug.

If the old plug is good and requires no replacement, tightening the plug once should be enough. A quarter turn after it seats will suffice.

If you are replacing the old spark plug with a new one and are installing a new plug, you need to tighten it twice to prevent loosening.

First, tighten the plug, a half turn after it seats. Then, loosen the plug. Next, tighten the plug again, a quarter turn should suffice this time.

Related Questions

How often should you get your motorcycle serviced? For motorcycle servicing, it is best to refer to the owner’s manual to find the recommended servicing frequency. As a general thumb rule, it is advised to service the motorcycle for every 3000 miles (or 5000 kilometres) of distance traveled.

How often should you clean motorcycle carburetor? The motorcycle carburetor should be cleaned once a year (every 12 months). In addition, the carburetor should be tuned and adjusted for idle speed every 6 months.

What are the effects of a masked spark plug? A masked spark plug with excessive carbon deposits will not ignite the fuel properly in each combustion cycles. As a result, there will be uneven acceleration in the motorcycle along with the wastage of fuel. The mileage and fuel efficiency of the motorcycle will go down drastically as well.