Whether we put our machines to work or play, improving our fuel efficency and monitoring engine performance are the last things on our minds. Unfortunately, power and performance does become a priority over time. So it's good to know how to read components that play a roll in improving your machines.

Photo credit: Yamaha Motors USA.


Reading your spark plugs can provide a wealth of information

Have you ever actually taken the time to read your spark plugs? I don’t mean the writing on the side.  I’m talking about the business end of the plug. Identifying the condition of the plug can help you troubleshoot or head off potential problems.

The first step to diagnosing any running issues or performing normal maintenance is to pull your spark plug and get a good read on what’s going on inside your engine.


Here's what to look for when checking out the bottom of the spark plugs:


#1: Good Color

A grayish-tan color tells you that your engine is operating at normal temps and your air fuel ratio is correct. This is a good thing! If this is what you see, no further action is necessary.

Step 1: Open your electrical connectors


#2: Chips or Cracks

If you see a chipped or cracked insulator, you're experiencing what's called detonation. But more important than the name, it's telling you that you either have a timing issue or you're using fuel with too low of octane (upgrade at the pump!).

STEP 2: Apply liberally to both ends of the plugs


#3: Oil

If you see smoke from your exhaust, you will probably find your plug black and coated in oil. This indicates you have oil leaking past your valves or piston rings. Your plug is fouled. If this continues to happen after replacing your plug, a top end rebuild may be necessary to cure this problem.

STEP 3: Reconnect your electrical connectors


#4: Melted Ground Electrode

If you have a melted ground electrode, you're experiencing pre-ignition. This is commonly caused by a lean fuel mixture, advanced timing, or wrong heat range spark plug.

STEP 4: Wipe off excess sealant


#5: Carbon Buildup

The most common is the carbon fouled plug.  You will find the plug covered in black, sooty, dried carbon all over. This tells you it is running too rich or your ignition system is weak.

STEP 4: Wipe off excess sealant 



This is a simple maintenance task that can be completed by just about anyone. Unless you don’t have the time, there’s no need to bring your vehicle into a dealership for this maintenance. If your vehicle is going in for service, be sure to ask them to check your spark plugs for you.




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