A motorcycle spark plug is a fundamental part of your motorcycle’s ignition system. It is important for the ignition system because it creates a spark that is needed for your motorcycle to start. With that being said, in this article, we will explain a working principle of a motorcycle spark and why it is important for your bike.
So how does a motorcycle spark plug work? A spark is created by voltage delivered in the plug from its base shifted from the center electrode to the grounded electrode. The spark plug ignites the fuel-air mixture inside the combustion chamber, leading to an explosion that starts your motorcycle engine.
Further in this article, we will cover all the topics related to the spark plug and spark plugs parts.
Table of Contents
How Do Motorcycle Spark Plugs Work?
Spark plugs are responsible for creating sparks that ignite the fuel-air mixture just at the perfect time. The spark plug must send the proper amount of power needed to ignite the fuel-air mixture. Electrical energy needs to be sent through the spark plug, which creates a spark that ignites the fuel-air mixture in the combustion chamber. Spark plugs can only remove heat, and they can’t produce any heat, which means that a spark plug is a heat exchanger. It removes thermal energy (if there is more thermal energy than needed) from the combustion chamber and sends that heat to your engine’s cooling system.
Spark Plug Parts
In this section, we will make a list of spark plugs parts, and we will start from the spark plug thicker end and continue to the narrow end. So a spark plug consists of the following parts:
- grounded electrode
- center electrode
- insulator’s nose
- threaded piece
- gasket
- metal shell
- hexagonal piece
- top insulator piece
- corrugated ceramic section
- terminal nut
Spark Plug Key Measurements
You need to know what measurements are suitable for your motorcycle, and in this section, we will give you the measurements you need to pay the most attention to.
Reach
The spark plug reach specifies how deep the spark plug gets into the cylinder. The distance must be correct, and that is why you need to measure it, so you don’t have any problems once you intend to install your plugs. If the spark plug is longer than it needs to be, it can lead to pre-ignition, get stuck, or there is a possibility that it hits the valve inside. On the other hand, if the spark plug is too short, it may not be effective, and your bike won’t even start.
Heat Range
Your spar plugs heat range is written on the side, and it is defined by the distance from the ceiling ring to the insulator’s tip. If the distance between the tip of the insulator and the ceiling ring is longer, it defines a hotter spark plug, while if that distance is shorter, it defines a colder spark plug.
Note: A spark plug that is too hot can cause pre-ignition, while a cold spark plug can wear out faster than the hot one.
Diameter
If your spark plug doesn’t meet the diameters needed for it to fit your motorcycle, you won’t be able to install it because it won’t fit into the combustion chamber. That means that you can damage the spark plug while trying to install it, or it can even damage the internal components of your motorcycle.
Spark Plug Gap
A spark plug gap refers to the distance between the grounded and the center electrode. The size of the spark is determined by the gap size, which means a bigger gap leads to a bigger spark. On the other hand, a smaller spark is created if the distance is shorter, which means the fuel-air mixture will probably be less burnt. Every manufacturer determines the spark plug gap size distance for their motorcycle type.
Note: If the gap is bigger, it requires more voltage to produce the spark.
How to Recognize a Broken or Not Functional Spark Plug?
There are spark plug testers that you can get online. You need to detach the high tension lead out of the spark plug and connect the boot of the tester to the spark plug and the tester stiff end to the boot on the high tension lead of your motorcycle. Start your engine after you have completed all of that.
How to Check Your Spark Plug?
You need to separate your spark plug from the chamber while the other end of the spark is still connected to the motorcycle. Place the spark plug on the motorhead or some other bike’s metal part. Turn over the engine, and if you notice a spark, that means that your spark plug is functional and working. The color of the sparks should be blue, and they need to be insensitive. It is not a good sign if the color is orange or if the sparks are intermittent.
Battery Problems
In some situations, the battery will be a problem and not your spark plug and what that means is that the battery doesn’t produce enough power that is needed for the spark plug to function correctly. Some inexperienced riders can instantly assume that they are dealing with a faulty spark plug while the truth is quite different, and you have a problem with your battery, not your spark plug.
Note: If you have any problems with your battery and need to change it, click on this link where we will lead you to step by step on How to Fix and Change Your Motorcycle Battery.
Your battery should show you at least 12.6V for it to be working correctly. You can get a multimeter and use it to measure your battery power. Another important thing you need to have in mind is your battery connectors; they need to be cleaned and well maintained so the power can get to the spark plugs.
Note: If battery connectors are not in good condition, the current can’t be shifted to the spark plugs in the amount needed for the plugs to operate at the optimal level.
Here is a nice video explaining how a spark plug works:
How to Clean a Spark Plug?
You can clean your spark plug in a couple of ways, and we will show you the most effective ways we clean it.
Wire Brush and Carburetor Cleaner
Using carburetor cleaner and wire brush is an effective way to clean debris and dirt from your spark plugs. You need to apply the carburetor cleaner to the spark plug’s head and once it is soaked enough, use a wire brush to remove debris and dirt from the spark plugs.
Sand Blaster
You can buy a special sandblaster unit and use it for connector cleaning. In this type of cleaning, there is a possibility that some of the black media that you will use can stay in the spark plugs and can get in the engine. Once you have finished sandblasting, you can glaze the ceramic insulator over it.
Blowtorch
You can burn away accumulated debris from the electrodes using a blowtorch.
Note: It is possible that you will have to re-gap the spark plugs before reinstalling them after you clean them with any of the methods we explained to you above.
When Should You Buy a New Spark Plug?
If you clean your old spark plug, it can function just like a new spark that you bought in a store. On the other hand, if you are low in experience and have never changed or cleaned a spark plug, we recommend getting a new spark plug.
Tip: If you need any help with changing your spark plugs, click on this link to an article that will show you How to Change a Motorcycle Spark Plug.
Installing a New Spark Plug
When reinstalling your spark plug, you first need to remove the spark plug cap. Use a wrench to take off the old spark plug. In this process, it would be wise to use a rag to cover the hole after you removed the spark plug and the reason for that is to prevent any debris or dirt from getting into your motorcycle engine.
Take a new spark plug, place it in the position, and use your hands to tighten it first. Later on, take a spanner and use it to tighten it a little more, but don’t overtighten the plug because you can damage it, and then it won’t function properly.
How to Change the Spark Plug’s Gap Size?
You can measure and change the gap size of your spark plug with tools designed for spark plug gaps. Use your motorcycle manual to know the gap size of your spark plugs, and make sure you follow it as specified.
Note: You need to be careful while adjusting the gap because the insulator, the center, and ground electrodes can easily get damaged and disrupt your spark plugs functionality.
Conclusion
The ignition system wouldn’t function without the spark plugs since they are responsible for igniting the fuel and starting your engine. Who would think that a part so small and tiny could have such a big significance not only for the ignition system but for the entire motorcycle.
We hope that this article has helped you understand a spark plug and how significant it is for your motorcycle. Make sure to check your spark plugs on the first sign of having difficulty starting your engine. If you check your spark plugs on time, you will save a lot of time and money since you won’t have to deal with unnecessary work.