If you own an ATV, there’s a good chance you’ve heard of stators. They’re an important part of your vehicle; unfortunately, they can also fail often.
In this post, we’ll go over the most common bad stator symptoms on an ATV, so that you can know what to look for if your stator starts failing on you.
Bad Stator Symptoms (ATV)
While the stator on your ATV is designed to last for a long time, it’s not uncommon for them to eventually fail. If your stator does start to fail, there are a few different symptoms that you might experience.
1. Weak Charging Voltage
One of the most common bad stator symptoms is a weak charging voltage. If your stator is tired and isn’t working properly, it won’t be able to generate the high levels of AC voltage that your ATV needs to run.
This can lead to a number of problems, such as your headlights being dim, poor idle, and even misfiring, due to a weak spark.
2. No Charging Voltage
Now, it’s quite rare for a stator to fail completely, but it does happen from time to time. If your stator fails completely, you’ll lose all charging voltage and your ATV will eventually die on you.
This is usually pretty easy to notice, as your headlights will get progressively dimmer until they eventually turn off and the engine stalls.
3. No Spark
While most stators are tasked only with supplying electrical power for the ATV, some ATVs also have a stator that’s responsible for powering the CDI, which is responsible for creating spark.
If your stator is failing, it’s possible that you’ll lose spark and the engine won’t start. This is usually accompanied by other bad stator symptoms, such as a weak charging voltage.
4. Rough Idle
Another common symptom of a bad stator is a rough idle. If your stator is having trouble generating power, then the engine will only produce weak spark, which makes the engine run rough and misfire.
5. Dim Headlights
If your stator is bad, it’s possible that your headlights will appear dimmer than usual. This is because the stator powers the electrical accessories and the ignition system on your ATV, and if it’s not working properly, then the only source of electrical power will be the battery.
6. Sluggish Acceleration
Another side effect of a bad stator is poor acceleration. If your stator is not producing enough electricity, then the ATV will only be powered by the battery.
The battery is not designed to power the entire ATV for long periods of time, so it will quickly start running out of juice, and you’ll notice that the ATV feels sluggish and doesn’t want to accelerate.
What Is an ATV Stator & What Does It Do?
If you need a refresher, the stator is responsible for generating electricity on your ATV.
Simply put, the stator is the stationary half of the ATV’s 3-phase generator (or alternator). The rotating half of the alternator (rotor) spins around the stator, and induces an electrical current inside the copper windings of the stator.
This electrical current is then rectified to DC, stepped down to around 14.5V, and sent to the ATV’s battery, where it’s used to power the electrical accessories and the ignition system.
Also Read: What Does a Stator Do on a Motorcycle?
How To Test an ATV Stator With a Multimeter
Luckily, testing the stator on an ATV is very easy, and the only thing that you will need is a multimeter. That said, a service manual for your specific ATV would be very useful in order to know the exact specifications of the stator, but it’s not necessary.
1. Stator Short to Ground Test
Start by locating the stator wiring harness. It’s usually made up of three yellow wires, which exit the generator cover and snake their way to the Regulator/Rectifier.
Once you’ve located the stator wiring harness, disconnect it from the stator.
Then, using your multimeter, set it to the ohms function and check for continuity between each of the three stator leads and ground. We recommend back probing the connector if possible.
If there is continuity, then the stator is bad (coils melted and shorted to ground) and needs to be replaced.
If there is no continuity, then the stator is good and you can move on to the next test.
2. Stator No Load Performance Test
The next thing that you’ll need to do is check the stator output to see if it’s within specifications. This is where a service manual would come in handy, as it usually has the specifications for the stator output.
If you don’t have a service manual, then don’t worry – most ATV stators should be outputting 70 VAC or more at cruising RPM. If your measurements are lower than that, it’s pretty likely that the stator is tired and needs replacing.
To do the no load performance test, disconnect the stator wiring harness and make sure that your ATV is in neutral and that it won’t roll away.
Start the engine and hold the throttle at cruising RPM (around 3000 RPM). If your ATV has a carburetor, you can adjust the idle to cruising speed or use the choke.
Once the engine is at cruising RPM, set your multimeter to VAC and measure the voltage between the three stator wires – a total of three measurements. Again, if the stator output is lower than 70 VAC, then it’s bad and needs to be replaced.
Final Thoughts
If most of the symptoms above apply to your ATV, but the stator test results were good, then the actual problem might be with the regulator/rectifier.
The regulator/rectifier is responsible for converting AC from the stator into DC, and then lowering the voltage to around 14.5 V. However, testing the rectifier is much more difficult, and it can only be done by the elimination method – we go into more detail in this article.
Hopefully, this article has helped you diagnose the problem with your ATV. If you’ve determined that the stator is bad, then I would recommend replacing it as soon as possible.
A bad stator can cause all sorts of electrical problems on your ATV, and if left unchecked, can lead to a total loss of electrical power, which can strand you in the middle of nowhere.
Thanks for reading!
Nick Kowalski is a diesel mechanic by trade, but his passion lies in motorcycles.
He’s been riding them since he was just a wee lad, and he loves restoring old Japanese street bikes and ATVs in his spare time.
Nick is an adrenaline junkie at heart, and he loves nothing more than hitting the open road on his motorcycle.