Do Motorcycles Have Alternators?

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All motorcycles, from your standard run-of-the-mill Honda to the ever-elusive Harley Davidson, need a source of electricity to run.

This current is needed by the motorcycle’s electrical system to power the headlights and blinkers, but the system itself can be a real frustration to understand.

With many fancy terms found when researching the electrical system of a motorcycle, the alternator is probably the most common term you may have heard of.

Despite being an essential part of the motorcycle, many motorcycles still have the misfortune to raise the question,” do motorcycles have alternators?”

Overall, all have no idea how the component works or can even find it in the motorcycle. If you are also in this boat, then worry not, as the simple answer is yes, motorcycles do have alternators, and in this article, I will be explaining all the essentials of the alternator.

Finally, moving forward, I will also provide various tips and advice to properly maintain the component as well.

What Is A Motorcycle Alternators?

Learn how does a motorcycle alternator work

The first alternator was created back in 1832 and has become an integral component in the automobile industry, being a huge and crucial component for electrical systems regardless of whether in a motorcycle or a car.

However, the inclusion of the alternator in vehicles started in the 1960s when cars and motorcycles would have them included in their electrical systems. The alternator gets its name for its function, which is to alternate current.

Like the alternator, many motorcycles have a component called a stator that is quite similar to the alternator but is less complicated and, in some cases, is the component of an alternator.

Some people even consider the stator the alternator itself, which is a misconception. While the motorcycle’s battery is also a very necessary part, the motorcycle cannot run on the motorcycle alone and so is aided by the alternator.

I will talk about this more in-depth later in the article!

Types Of Alternators

As hinted at above, there are two main types of alternators that you can find in your motorcycle; one Alternator/ Automotive Style Alternators and the 3-piece Alternator.

The Automotive Style Alternator is also known as the one-piece alternator because this alternator type has all of its components self-contained into one single unit.

This means that you need not go through the hassle of inspecting every component of the alternator and instead can focus on one single unit.

This type of alternator is widely used in larger touring bikes such as Harley-Davidsons, Hondas, and Kawasakis.

This type of Alternator also has the advantage of being simple to have serviced and can save you on labor costs when taken to the mechanic.

The other type is the 3-piece alternator, which is divided into three pieces as per the name. This type of alternator has the advantage of having each of its parts cleaned individually and inspected accordingly.

This can save you a lot of money if you have only one of the three parts, causing some problems as you can simply replace that specific part instead of purchasing an entire unit.

The Stator Vs. The Alternator: How Are They Different?

As mentioned above, many people have difficulties understanding the difference between the alternator and the stator. So they rather confuse the two or think that both are the same.

The alternator and the stator differ because the stator is one component of the alternator, and the alternator is, in fact, a collection of components that among the stator include two other parts.

While this is the 3-piece alternator that contains the stator as an individual component, the one-piece alternator is its unit. It is externally mounted near the engine while the stator is found inside it.

Another key difference is that the stator uses a permanent magnet while the one-piece alternator uses an electromagnet.

All of these differences should help you decipher which alternator type you have and should also clear any issues or confusions you may have when talking about the stator or the alternator in your motorcycle.

Purpose And Problems In The Alternators

The alternator is designed to provide the brunt of the electricity needed by the motorcycle after the initial spark of electricity provided by the battery for ignition.

This is done this way so that the motorcycle battery has room to recharge and the motorcycle does not drain the battery completely.

How Do Motorcycle Alternators Work?

Although the main electrical component in any vehicle, motorcycles included, is the battery, its job is to start the vehicle and provide electricity to components like lights and horns. The alternator produces the electrical energy needed to drive the vehicle.

Generally, in motorcycles, after the motorcycle has been started, the battery usage is almost completely cut off, and the alternator takes over. The electricity produced by the alternator is used to charge the battery itself as the vehicle runs.

In layman’s terms, the alternator is a component that is supposed to convert mechanical energy to electrical energy. It does this with the use of magnets.

To produce current using magnets, you need to rotate them to get the electrons moving in the coil wire that surrounds the magnets.

This rotating motion in other vehicles is made by the engine’s drive belt, which is connected to the rotor shaft of the alternator.

However, the rotor is connected directly to the engine’s motors in motorcycles. The engine powers this drive belt.

This causes the rotating motion for the magnets allowing the flow of electricity in the coil wire. It is important to know that since this component is responsible for controlling and producing electricity for the vehicle, it is supposed to be safe from any contact with water.

Function Of Alternators In Motorcycle

As mentioned above, the job of an alternator is to provide electrical power to the motorcycle, which is done using the motion provided by the engine, the magnets on the rotor, and the coil wire that carries the current.

However, the one thing that was not mentioned was that motorcycles, like many other vehicles, need direct current. This is because the direct current is required for all components to run without any hitch in the flow of electricity.

The problem is that alternators produce alternating currents. This needs to be converted for the motorcycle to work properly. This is why alternators in every motorcycle are used coupled with regulator rectifiers.

These are used to convert alternating current into direct current, which is required by the motorcycle. The direct current is then used to power all sorts of electrical components of the motorcycle.

Where Can You Find The Alternator In The Motorcycle?

The alternator of a motorcycle is usually found near the starting gear of the motorcycle. This is close to the engine of the motorcycle.

Since motorcycles do not have drive belts, the rotor needs to be connected directly to the engine. The covering case is usually the one with a round-looking surface.

This cover is metallic and tightly sealed to ensure that the alternator does not get damaged by making contact with water.

Since the cover is metallic, removing it will require a bit of prying and probing because the magnets in the alternator will try to keep it in place.

If the alternator needs to be removed, you will need specialized tools to do so and make sure that it is done in the right order when putting it back together.

This is because the alternator’s rotor needs to be set so that only it can be moved by the engine and not the other way around. For this purpose, there are cranks installed to prevent the alternator from moving on its own.

Common Problems Of Motorcycle Alternators

Like all electrical components, alternators in motorcycles are prone to face some problems. Some of the things that you might face that are caused by the most common issues with alternators are:

  • The battery gets cut off
  • Not reaching the full capability in terms of RPM
  • Dimming of headlights
  • Unusual whirling sounds

The battery getting cut off could be because of the battery not getting charged by the alternator. The battery has a limited amount of electricity stored.

So if the alternator is not working properly, it might not charge the battery enough or at all in some cases. The alternator not producing the right amount of current would mean that the motorcycle has lower electricity to work with.

You might face low speeds and RPM. If the motorcycle’s alternator dies completely, the motorcycle can come to a complete halt.

The magnetic brushes used to generate the electricity being damaged or worn out can mean that you might hear unusual noises from the alternator.

Either of these situations is problematic, so you should get your motorcycle checked if you are facing something like this.

If you feel as if you are suffering from a faulty alternator and are not sure if you want to take your precious motorcycle to the mechanic, then make sure to read the rest of the article as I will be going over a few tests on how you can see if the alternator is working as intended.

Alternator Testing And Maintenance

Here are a few ways you can test the durability and strength of your alternator and a few good habits to develop so that it can have a long and problem-free life.

Voltage Test

You should carry out an AC test now and then to ensure it is running perfectly. Once you locate the stator in the motorcycle, hook up a multimeter to test the voltage.

Then find the stator’s connector and carry out an AC test. After this, you must make sure that the battery’s voltage is fine while the battery is off.

Test the voltage again once the engine is on. This time, the voltage should be higher. If all is going well and your alternator is operating as intended, the readings should be around 14 volts, and both readings of the voltage on each terminal should match each other.

If the reading is not as expected or if the readings do not match, then you probably have a defective component, rather inside the alternator or the alternator itself. Either way, you should visit the mechanic to have the problem fixed.

Manual Test

This test is much more straightforward than the previous one and requires little to no understanding of how the components of the motorcycle function or how to use a multimeter.

This test depends on the motorcycle’s headlights and how bright they glow when the motorcycle is revved up.

Revving up the motorcycle and the lights increasing is a sign of a healthy and working alternator. If you think you are having alternator issues, consider running your motorcycle and revving the engine in neutral.

If the lights glow brighter the more your rev the engine, it is a sign that your alternator is working fine. If this is not the case, you may have a defective alternator, in which case you should have it checked out by a professional.

Regular Maintenance And Servicing

Sometimes the damage on the alternator is visible and can show you the problem just by looking at it. Once you remove the side covers of the motorcycle and inspect the motorcycle alternator.

You should be looking for the following:

  • Worn out wires
  • Burn marks
  • Melted components

If your alternator has any of these, it needs fixing. Engaging in regular maintenance of the bike, in general, is good as it not only allows you to find issues like these early on so that you can fix them before they grow.

It also helps to make sure that these problems do not happen at all and keeps your motorcycle running at the best performance.


Yes, motorcycles do indeed have alternators. They are a very important component of the motorcycle’s electrical system.

Without them, your motorcycle would have its battery drained all the time, and you wouldn’t be able to power the headlights and carry out other electrical functions.

Similar to all integral components of the motorcycle, it needs maintenance and is worth any repairs and upgrades so that you can make sure that your motorcycle runs perfectly.

After reading this article, you should be no longer having the question of do motorcycles have alternators and should be well versed in how they operate. You should also know how you can make sure yours is running fine.

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