Does your motorcycle have a wet spark plug? What does it mean, what is the cause and how to fix it? This will all be covered in this article, so keep reading ... A wet spark plug is simply a spark plug with a wet insulator and ground electrode and usually black in color when removed from the cylinder head of your motorcycle.
Motorcycle spark plugs - General information
There are a whole bunch of motorcycle spark plugs on the market that meet specific needs. So, before you get started, we advise you to take a look at our complete guide on the subject.
What happens when the spark plug on your motorcycle is wet?
The most common symptoms are spitting, poor performance, hard starting, or inability to start. Your motorcycle can also be flooded with fuel. If it is too wet, the spark will not be able to ignite the mixture and will eventually foul the spark plug. The result is a motorcycle that won't run or start.
Usually this means that the air-fuel mixture is too rich. Too much fuel (humidity) and the spark plug becomes dirty. A fouled wet candle will generally be black due to the rich mixture. This can easily be caused by the wrong setting, but it is not always the case. Common causes of a wet spark plug include the following:
- Low compression
- Exploded cylinder head gasket
- Incorrect fuel
- The starter is still in place
- The engine was flooded
- Setting too rich
What Causes a Wet Motorcycle Spark Plug and How Do I Fix It?
Now that you know the possible reasons why your motorcycle's spark plug is wet, it's time to figure out how to fix it. Let's look at each cause to determine the root of your problem.
You need to troubleshoot it so that you don't start replacing parts without knowing where the real problem is. It's best to do one thing at a time and test to confirm your repair. This can save you a lot of money and time in the long run.
First cause: a compression problem
Low compression means the engine cannot compress the air-fuel mixture to burn it properly. As the mixture cannot be fully compressed and ignited, some of the fuel is not burned.
This results in excess smoke from the exhaust, carbon build-up on the piston and exhaust port, as well as a wet spark plug.
Low compression is most often due to high end wear. You can test the compression to see how it compares to the original one. A closer inspection should be done to determine what exactly is worn in the upper part of the engine.
A wet motorcycle spark plug from an exploded cylinder head gasket
Exploding a cylinder head gasket can cause a wet spark plug. Coolant can seep into the cylinder and enter the air-fuel mixture. The motor then malfunctions and may make a different sound. If your spark plug is wet, quickly check the coolant level. A low coolant level can mean the head gasket has burst.
Head gasket available on Amazon
Bad fuel can make a motorcycle spark plug wet
Using the wrong fuel or poor quality gasoline may cause a wet candle. Higher octane fuel, such as racing gasoline, will be rich and wet the spark plug over time if not set properly.
Use the octane recommended by the manufacturer for your engine. A higher rating does not produce more horsepower, unless the compression ratio is higher than that of stock gasoline. Premium 91 octane pump gasoline is generally sufficient for most dirt bikes.
Poor fuel quality can also cause problems. Gasoline degrades by breaking down and absorbing moisture from the air over time. It is best to use fuel without ethanol because it lasts longer before it degrades. Bad gasoline from a rarely used pump station can also occur.
Fourth cause: the starter is still running
Everyone did it. Did you forget to turn off the choke?
The choke allows more fuel to enter the mixture, which is great for starting a cold engine, but the mixture will be too rich and perform poorly after the engine is warmed up. If your spark plug is wet, quickly check to see if your choke is inactive and functioning properly.
The spark plug is wet from a flooded engine
If the engine is flooded, the spark plug will certainly be wet. Engine flooding can occur when your motorcycle overturns if it is equipped with a carburetor, when it takes too many kicks to start the motorcycle, or when the engine stalls if the tuning is too rich. To repair a flooded engine, turn off the gas, tip the motorcycle upside down to release any excess gas, then let it sit for at least several minutes to evaporate the gas. You will likely need to keep the throttle wide open for the motorcycle to start with a flooded engine.
Our recommended products for a wet motorcycle spark plug:
To conclude, here are some recommended products on Amazon:
