Your Motorcycle Spark Plugs Have Something To Tell You

Your bike is running like hell.

It happens.

But here’s the real problem. You hate having someone else do something you can do perfectly well yourself.

So how do you figure out what’s going haywire? Take a look at your spark plugs.

A look at the color and condition of  your plug or plugs can give you a critical insight about how your engine is running. One look can tell you how well-tuned, or how far out of tune, your ride may be.

What Your Spark Plugs Are Trying To Tell You If You’d Only Listen

What can your spark plugs tell you? First, you can find out if your engine is running too lean or rich. Second, a look at them will tell you if your rings are taking a crap. They can tell you if your bike’s running too hot or cold. You might also get some insight in the quality of fuel you’re using. You might find out you have some debris in your engine.

Use theses descriptions of plug condition to help you figure out what to look for and how plug condition effects your engine performance.

If your engine is performing correctly, your plugs will let you know. A properly tuned engine will have a light tan, brown or grayish colored electrode, base ring and porcelain. You might find a little soot on the electrode (and it looks like charcoal) is not a bad thing. Most of the time, a little black soot is fine, but depending on specs and your particular engine, it might mean your bike is running a tad “rich.”

Running rich means you  have too much oil and or fuel in your mixture, and it can “foul” your spark plug. If the problem is fuel, the spark plug electrode will be covered in a dry soot. If it is, you’re running a spark plug or engine tuned too cold. If you have too rich of an air and fuel ratio or you run your bike with the choke on for too long, this is what you might see.

If the end of your spark plug is wet and black, your spark plug is fouled, my friend. It will look like you dipped the end the plug in a pan of used oil. It’s also a likely indication that your fuel and oil mixture are too rich, and an incorrect setting of your oil injection system. The really bad news is that it could also mean have worn rings or valve guides, and that signals the time has come for a rebuild.

If your engine is running lean, the plugs will tell you as well. Lean or hot running engines will leave your plugs with a whitish residue and they might also have a blistered-looking or melted electrode. You might be using a plug that’s too hot, that your engine timing is advance too far or that your engine’s air and fuel mixture is too lean.

Here’s a handy-dandy series of pictures to help you understand how a spark plug will look if things go wrong – and why they went wrong.

A couple of tips? Warm your engine up to operating temperature before you pull the plugs. And by all means, if the plugs seem tight, take care when trying to remove them. Be gentle. If you apply too much pressure and damage the jugs or threads, you’re walking, my brother, and probably searching the classifieds for a new bike or some expensive parts.

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