Unraveling Electrical Mysteries: What is a motorcycle Stator, and What Does it Do?

Even the most seasoned motorcycle rider may not recognize what a stator does or where it is on the bike. But this part can have a significant impact on your bike’s overall performance and longevity. Here’s what you need to know about your bike’s electrical equipment, including answers to questions like what is a stator and what does it do?

What is a Stator?

You can find stators in many types of electric generators, motors, and rotors. A stator is also the part of the alternator that’s stationary (while the rotor, also called the flywheel, moves). Alternators generate power through alternating current (AC). Stored power in the vehicle battery must be DC, however, requiring regulator conversion to keep your bike powered up.

The stator component is round, containing a coil with metal flywheels. A stator has electromagnets, as does the rotor, but the patterns are opposite. The same way magnets of the same polarity repel one another, so do the electromagnets in the stator and rotor. As the magnetic field of the stator rotates, the magnet rotor must go along with it.

Traditional alternator assemblies are standard and handy because they deliver higher power at lower speeds. They do require batteries for power, however, which is a potential drawback in comparison with a motorcycle’s alternator system.

Because a stator generates its own electricity, motorcycles have systems which are relatively lightweight compared to those in a car or truck.

Are All Stators the Same?

Because motorcycles use different amounts of energy, not every stator is alike. The stator must produce the appropriate amount of energy for the bike, leaving lots of room for variation, especially when looking at the power and torque differences between a 3 wheel motorcycle and a traditional two-wheel bike.

Plus, some stators generate AC power solely for the ignition, and others produce power (which then converts to DC power) for other utilities on the bike. Fuel injection, lighting, and ignition computer components often use DC power on a motorcycle.

Other stators can include a pickup coil or pulser, an additional part which mounts near the motor. A pickup coil can sense the crank angle, and it also “sends” its data to the ignition computer, which calculates spark timing.

Do Motorcycle Stators Require Maintenance?

Like any other system on your bike, the electrical charging components do benefit from some attention now and then. Stators, in general, don’t require much attention, but the other parts of your electrical system do.

If you don’t have experience working with electrical systems, however, you may want to leave these types of tasks to a professional. Working with electricity can be dangerous, so it’s crucial to always follow manufacturers’ safety precautions when disassembling your bike’s electrical parts.

Fortunately, it is possible to swap out most parts and revitalize your project bike or daily driver. The key is knowing what you’re looking at and recognizing potential issues. For reference, here’s an overview of your motorcycle’s electrical system components.

Motorcycle Electrical Systems

Recognizing the stator’s role in your motorcycle’s electrical system can help you understand not only how power generates in the bike, but also where to look when something stops working correctly.

Generally, a motorcycle’s electrical system includes:

  • A battery
  • The alternator
  • A rectifier/regulator
  • Wiring
  • Fuses

You know the battery stores and delivers energy and the alternator generates power via electromagnetism. But the rectifier/regulator converts the alternating current (AC) into direct current (DC) for storage in the battery.

Wiring and fuses aren’t technically components of the electrical system, but they are essential for tempering and transporting energy. And of course, fuses can create their own set of problems which require replacement—and often.

Motorcycle Batteries

A battery’s primary job is to start your motorcycle’s engine. Because the alternator isn’t running yet when you first rev the bike up, the battery must provide the powerup. As the RPMs increase, the alternator output elevates, and the system relies less on the battery’s power storage and more on the alternator’s power production.

Your battery also protects the electrical components on your bike from energy surges and spikes. You can think of it as a surge protector of sorts—the battery is the first line of defense against electrical overload, but if it burns out, the rest of your system should survive.

Alternators (and DC Generators)

Modern motorcycles use alternators, which provide alternating current. But older bikes harking from 1960 or earlier had DC generators. Therefore, used motorcycles may need a kickstart to get it going with DC power.

You’ll also find different alternator type on some other motorcycles, specifically larger bikes with more power (and therefore higher heat output). Exterior mounting and single-piece construction are giveaways here, and the alternator will more closely resemble a car’s alternator than what you may be familiar with as a motorcyclist.


Though the rotor and stator work together, the rectifier/regulator is also part of the alternator package. It’s worth highlighting here because you may focus on the rotor and stator as the main components of the alternator, but the rectifier has a purpose, too.

Rectifier/regulators modify the alternator’s power from AC to DC so the battery can store it. In older bikes, the rectifier and regulator unit might be two pieces, but modern innovation has melded them together into a more compact and convenient component.

You’ll usually find the rectifier/regulator somewhere with a lot of airflow since they produce a lot of heat. The casing and mounting of the unit also help the heat dissipate.

Technically, the rectifier/regulator is part of the alternator, but it’s helpful to highlight it separately as its function is different from the alternator itself.

How to Preserve Your Bike’s Electrical System

When it comes to maintaining your bike’s electrical system, you might assume that no news is good news. But just because your battery hasn’t taken a dive yet doesn’t mean you shouldn’t be checking out the electrical components to ensure proper function.

And while the stator itself may not require much attention, there are other preventative measures you can take to enhance your motorcycle’s battery life.

Inspect and Adjust the Battery

Checking your battery’s terminals and ensuring a strong (and clean) connection can help avoid breakdowns. You will also want to check the fluid levels in the battery and top off with distilled water as necessary.

Keeping the battery charged is also crucial, especially if you ride your motorcycle infrequently. Instead of leaving the battery attached to the bike, you might consider removing it and using a designated battery storage unit for longevity.

Check the Battery Voltage

Even if your battery visually looks good, it may not be. Checking the voltage is a smart habit, and it doesn’t require expensive equipment. You can purchase a voltmeter and verify your motorcycle’s battery output anytime, which could help you catch other potential flaws in the electrical system.

Look at the Rectifier/Regulator

There’s not much maintenance you can perform on the rectifier/regulator, but you can check to ensure the connections are tight and that the terminals are clean (and not corroded). Since a rectifier/regulator relies on plenty of airflow to keep from overheating, make sure it’s properly mounted and no debris blockages are affecting its performance.

Some rectifier/regulators tend to “go out” without much fanfare, and past models of the Triumph Bonneville fall into this group. Thankfully, parts are typically easy to obtain and replace, even if the repairs become a headache.

The good news is that even a worn down and underperforming electrical system isn’t a deal-breaker. When it comes to used motorcycle values, you might find a decent bike which is still affordable even given the electrical overhaul it requires.

Even if you’re shopping for an older bike, checking out the electrical system—and budgeting for potential repairs and upgrades—can help you make a smart purchase.