One way to find out if your spark plug is fouled is when its electrodes are black.
Blackened electrodes can mean one or two things: carbon fouling and oil fouling.
Blackened Spark Plugs
Spark plugs can become blackened for several reasons. Depending on how they appear, it will give you a clue about what caused it and what you should do about it.
That is why it is critical to learn how to read the condition of your spark plugs. A fouled spark plug with blackened electrodes can cause one or more of the following problems:
- Engine misfires
- Engine stalls
- Reduced gas mileage
- Slow acceleration
- Hard starts
Causes Of Spark Plug Fouling | Maintenance Minute
A carbon-fouled plug can mean you have a rich air-fuel mixture in your cylinder.
Too much rich air-fuel mixtures can leave the plug tip with excess carbon deposit, and that excess carbon accumulates on your spark plug.
Symptoms: Dry soot on the electrodes and insulator tip; gray to matte black.
Remedy: Try consulting a mechanic for the required replacement for the damaged plug.
An oil-fouled plug indicates that oil is leaking into the cylinders. The leak is usually due to worn pistons or valve seals that allow oil to pass through.
Symptoms: Wet texture on the electrodes and insulator tip; oily and black.
Remedy: Replace the damaged plug and seek help from a mechanic to find the source of the leak.
Frequently Asked Questions
What can I do to prevent my spark plugs from turning black?
Here are some potential solutions to this issue:
- Clean your spark plug – You should clean your spark plug frequently. Try doing this whenever you’re changing your engine’s oil.
- Fix air/fuel mixture – Set your mixture correctly. Your recommended ratio should be 14.7: 1.
- Narrow your spark plug gap – You have to reduce the gap of your ground electrode. Use a plug gap tool with this.
- Clean your air filter – A clean air filter can help prevent spark plug damage. Your recommended cleaning material should always be clean water.
How do I fix carbon-fouled spark plugs?
Although it’s wiser to replace fouled spark plugs, it’s possible to fix this problem. You can:
- Sandblast – You can scrape carbons off the plugs using a machine that shoots sand out with a jet of air.
- Use abrasives – You can also scrape off the carbons from your plug with abrasives such as sandpaper or a wire brush.
- Use treatment products – Products are available on the market to clean your carbon-fouled plug.
- Using a butane torch – Burning off carbon is another effective method for repairing your plug.
How to “Read” your Spark Plugs | Goss’ Garage
Why do black carbons accumulate on my bike’s spark plug so frequently?
- One reason could be that it’s a clear indication that your bike isn’t properly tuned. In other words, your bike isn’t completely burning the fuel/air mixture.
- Your spark plugs may be old. If so, you should consider replacing them with new ones.
- You have contaminated oil. If your oil is dark and thick, it could be contaminated with dirt. Take this as a sign that your engine’s oil needs to be changed.
- Another possibility is that you have some internal leaks. These leaks could include oil, fuel, and air leaks.