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How to test motorcycle stators? Volt Check & Connections

Motorbike engine and fuel tank on street

A stator is a part of the motorcycle’s alternator that doesn’t move; it’s the main electrical system that motorcycles use. You need to remember that a stator is very important when giving power to motorcycle accessories that need electricity. The question is, how do you test a motorcycle stator? That’s what we will talk about in this article. 

If you are new to motorcycles, it’s necessary to understand what a stator, rectifier, and regulator are and how they operate. More importantly, it’s also essential to know how to test them regularly before failing. 

With a high-quality multimeter, you can check the motorcycle stators even when installed on the bike. The tests are essential, as these will help you identify or even eliminate the vehicle’s stator as the significant problem in the charging issue.

Motorcycle Alternator Versus Stators

The “alternator,” which has been around since the turn of the century, was designed to power a dynamo at first (also known as a generator). Still, today, we use it to generate electricity by converting mechanical energy into electrical energy. The alternator is part of the battery-charging system, and it will need replacing every couple of years.

Motorcycle Alternators and Stators: The Basics

An alternator converts mechanical energy (rotation) into electrical energy. An alternator consists of a rotor, which rotates through a belt connected to the drive shaft. A stator is fixed in position and surrounds the rotor to form the electromagnet. The rotor has magnets around its circumference, and the stator has coils of wire around its surface.

Motorcycles produce power in the same way as automobiles do. They do it, though, in a somewhat different way. Instead of having an externally-housed alternator, a stator is housed within the motorcycle’s engine.

Aside from the stator, the rectifier/regulator also trims the raw output current to avoid overcharging the battery.

What are the signs of a faulty motorcycle charging system?

A faulty charging system can be just about any number of things, from charging problems to a broken battery. The symptoms can be different for each motorcycle. Still, it’s usually not that difficult to tell if there is an issue.

  • Your bike won’t start. Your bike just turns over slowly, or you hear a click but no response from the engine. 
  • Sputtering. It’s challenging to keep the engine running when the bike is low on voltage. 
  • Your lights light up but dim as you accelerate. A motorcycle’s lights should be constant, so this shouldn’t happen. 
  • Battery Warning Light. This is a clear indication of a problem with your charging system that needs to be checked. 

Problems with the Charging system

If your motorcycle battery fails to charge, more often than not, one of its components has an issue. 

  • Regulator/rectifier overheating: This component is responsible for taking the current from the alternator, then trims the voltage to the correct one and converting it to DC to charge your battery. There will always be an excess current, which turns into heat, so the regulator/rectifier comes with a big heatsink to help dissipate the heat, assisted by airflow to cool it down. However, after about 50,000 kilometers or about 1000 hours of operation, it’s understandable that the will need replacement. 
  • Battery Dies: Batteries do have a shelf life, and once they reach it, they die, primarily if they are not properly maintained. 
  • Other components damage the battery: This can happen if the regulator/rectifier doesn’t give the correct voltage output, overcharging the motorcycle battery
  • Stator Coil Dies: A separate alternator stops working, or a belt might have snapped. 
  • Wires are coming loose: Vibration does affect the state of many things on a motorcycle – nuts, bolts, and wires. 

How do you test a motorcycle stator properly?  

  • Voltage Check: 

If you’re detecting a low voltage on your motorcycle battery. In that case, using a multimeter will help you check the voltage. However, note that you may have to charge the battery if you do not have 12.5 volts. After this is done, check the cables and the contact points for corrosion and clean (or replace) them. Inspect the line for any breaks in the insulation as well. 

Statistic Stator Test:

This type of test tells you if the stator is in perfect working order. 

Dynamic Output Test:

This type of test allows you to check the rotor as it spins and magnets around the stator. A problem in the rotor will definitely cause a loss in output. If it happens, here’s what you should do:

  • Expose the stator and check it for any broken wires, insulation problems, or thermal damage on the Coil. Look for any damage which might be a sign that the stator is coming in contact with the rotor. 
  • Check the stator for remnants of any broken magnet. Depending on what you see, you may have to replace the stator. You also need to check the rotor itself for damaged magnets. Do note that the magnets cannot be replaced individually, so you will have to replace the rotor as a whole.

Other ways to Test a Stator

If you don’t know much about how to test a stator, remember that you should check the connector’s terminal tabs for continuity. Check if there is power by setting the multimeter to Ohms. You should utilize one of the multimeters leads to check the tab’s resistance by checking from A to B, B to C, and A to C.

It doesn’t take an expert to check the stator. With the tips mentioned above, you can check it anytime quickly, conveniently, and without cost. Of course, if you have any doubts, you can consult with an expert. 

Replacing the Stators

The stator comes in many designs for different motorcycle brands and models, but they all operate differently. As a result, selecting the appropriate unit for your motorcycle is critical.


Stators are the components responsible for generating the electrical current to power the motorcycle accessories. The stator must be in good condition and must be tested regularly to ensure that it’s functioning correctly. 

I hope this post has given you a better knowledge of how a stator works and how they are tested.

Feel free to leave any comments or questions.