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Discussion Starter #1 (Edited)
Hello!

While Kawasaki did a fantastic job building the Vulcan 900, arguably one of the best mid-sized cruisers out there, owners of the bike know that it has one rather annoying flaw; a seemingly defective stator design that simply does not last. Many stators will fail well before they should, and need to be replaced. After some discussion, research, dealing with the issue myself, and mentoring from our Vulcan Forums stator expert, Sfair, I've compiled the following list of information regarding the stator, preventative maintenance, and tests to determine your problem.

1. What is the Stator?

The stator is part of the charging system on your vulcan, and is the part most likely to fail. Inside the left side of your engine is a magnetic rotor, which spins with the engine, and a stationary bundle of coils, called the stator, which is bolted to the inside of the cover and, with the help of the rotor, generates electricity to keep your bikes electrical system running.


Pictured is a popular aftermarket stator replacement from Rick's Motorsports

2. What causes the stator to fail?

The most common stator failure is a 'short to ground' scenario in which something comes into contact with something it shouldn't, resulting in the stator eventually 'burning up'. This is very easy to test for, we'll outline this test later on in this post. In the Vulcan 900, the most likely cause of this is vibration that can cause coils to come loose, insulation to rub through, or even the stator wires themselves rubbing through and contacting the alternator cover (as was my case). The result is a short to ground which can reduce the stators output, as well as damage the stator. Eventually, it will lead to a ruined stator, that often gives off the famous "Alien Noise" when the bike is idling.

3. How do I know if my stator has failed?

We will outline the tests a bit later but the most common symptoms of stator failure are surging lights, especially at idle, and a fairly high pitched whining sound from the left side of the engine.

4. What does NOT cause the stator to fail?

There are alot of theories regarding stator failure, some that I myself have perpetuated on these forums. But, in doing research on how the system works, and talking with Sfair, I found a few of these to be myths.

I- Load. Excess load is not likely to cause the stator to fail. Our charging systems are a three phase AC system that is always at 100%. That little box below the radiator is called a Regulator/Rectifier. Part of it's job is to take the excess power created by the stator, and dump it to ground. The stator is always outputting the maximum amount of power it can, you won't 'overload it' and cause it to fail with driving lights, heated gear, espresso makers, etc. However, overloading can stress the stator and lead to potential problems down the road. You are more likely, however, to have a dead battery long before you have a failed stator. If you are not sure if you have your charging system overloaded, then follow these steps from Sfair:
"
Say you installed a light bar and you want to check that your charging system can handle it:

1. Run engine up the the speed that it normally turns at 30mph, 2500??? Use your ear as a guess if you have no tach.
2. Take a voltage reading across the battery.
3. Turn on the light bar and take another reading.
4. If the output drops more than a few tenths of a volt, then the alternator may not keep up under normal driving conditions. If it drops to 12v, then you have problems.
"
You can, however, use more energy than the charging system is producing, resulting in a dead battery. You could also overheat wires, blow fuses, or damage switches. So, it's a good idea to stay within Kawasaki's recommended 70w accessory maximum, and to use relay's, extra wiring, additional fuses, and et cetera when installing accessories. However, once again, too many accessories will not damage your stator.

II- Batteries. A discharged battery, or worn out battery, can potentially damage components in your bikes electrical system and create a significant draw on your charging system. Kawasaki recommends not 'jumping' your bike or driving it with a discharged battery. However, once again, a discharged battery, though something you shouldn't necessarily do, is not going to damage your stator.

III- Water. This is a common one and one I was convinced (and might still be). The idea being that water getting into the connectors on the regulator plug in the front of the bike burns up the stator. According to Sfair, heat and energy passing through the plug would evaporate any water that would actually create a short-to-ground condition, so quickly that it wouldn't cause any damage. To be honest, I still take precautions to keep water out of my regulator plug (can't hurt right?) But, according to Sfair, it's not likely that water in the regulator plug causes stator failure.

So, in conclusions, our stators fail because of vibration and wear on the physical stator over time resulting in a short. There may be a fault somewhere that gets damaged easily, or it might just not be well built. Whatever the case, the damage to the stator happens inside the engine, not outside the bike or by means of anything plugged into it!

5. How do you replace the stator?

It's not too bad, actually, but it does take some time. You will need;

1 New Stator (I recommend Rick's Motorsports Stators. They are cheaper, and seem to last longer than OEM)

1 new Alternator Cover gasket (Order online or through your dealer, not usually carried in-stock anywhere)

Silicone Spray to spray the gasket with before re-assembling the bike

Willingness to spend a few hours working on the bike and doing the tests outlined in this thread in order to be certain you won't deal with the same problem within a week!

You'll also need a handful of tools. There are threads on how to replace it and the Kawasaki service manual outlines the job nicely. I will work on getting a write up on how to do it in more detail but I will quickly outline how I did it (AS A QUICK OUTLINE to see if it's a job you're willing to undertake. PLEASE don't print this out and take it to your garage! I'm not responsible when you break something!)

0. Drain the engine oil completely

1. Remove the floorboard and shifter

2. Remove the chrome cover on the left side

3. Remove the pulley cover (closer to the rear wheel) and the alternator cover (closer to the front wheel). The alternator cover will drip some oil. Also, know that the stator is being held on by the rotor, there is basically a magnet holding it on. So, even though you'll get all of the bolts off of it, it will fight you coming off. It's normal, nothings caught, just pull it out as straight as you can, wobble it back and forth a bit. It'll pop off.

4. Remove the three bolts holding the stator in, remove the metal plate holding the wires away from the rotor, pop off the grommets, and cut the three white wires.

5. Installation is reverse of removal. I found it easier to mount the stator, run the wires under the plate, and then slide the cover back on to the bike with a couple bolts in to keep it secure. Then, I soldered the wires back together, finished assembling the cover, put the pulley cover back on, chrome cover back on, make sure the drain plug and oil filter are in tight. Refill with oil and go. (But don't assemble it all until you finish with the tests outlined below!)
 

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Discussion Starter #2 (Edited)
6. How do you test for Stator and Reg/Rect. Failures?

To quote Sfair, the stator failures are a vicious cycle. Often, a bad stator will take out the Regulator/Rectifier, which, in turn, will eat up the new stator. Both should be tested before firing up the bike. Also, if you're not sure WHAT is failing on your bike, the following tests will get you squared away.

Test 1 - Stator Voltage

Using a good quality multi-meter, set to AC Volts, (see the meters owners manual for proper placement of the leads and settings to test for AC volts. Improperly setup you WILL damage your meter with this test. AC volts. Not DC!)

Locate the regulator plug located at the front of the bike. Unplug it. Note the three white wires coming to the plug. Label them A, B, and C. Start the bike. (The regulator does not need to be plugged in for the bike to run)

Your meter should have a red and black probe. With the bike idling, touch the red probe to wire "A", the black probe to wire "B", and note the readings.

Do the same for wires "B" to "C"
Finally, "A" and "C". Once you have three readings, have someone rev the bike (or adjust the idle) to around 3,000 rpms. Repeat this test and note the readings.

On my bike, the readings at idle are 36v, and the readings at 3,000rpms are 56v. I was using a high-end meter I borrowed, some meters may be less accurate, and voltages may be slightly different than mine. If yours are alot different, then your stator is not outputting correctly. If you're not sure, be sure to ask in the forums.

If these voltages are not correct, replace the stator. If they are, continue on to test 2:

Test 2 - Short to Ground
For this test, an analog meter is best. Set it to ohms,

Short to ground is the most common stator failure, and it's easy to test for.

First, disconnect the positive battery cable. (Important! You could damage your meter if you don't)

Second, locate the plug under the seat near the battery that contains four wires (black, brown, red and white). Unplug it. This will prevent a false reading.

Next, short out your meter (set to ohms, touch the leads together) and be sure that it reads 0ohms when shorted. Adjust if necessary. Then, attach a lead to the black (negative) battery cable, then touch a lead to each of the three white stator wires, record the readings.

If you are shorted to ground, you'll get a reading expressed in ohms. Any reading other than infinite is bad (refer to your meters owners manual to learn how infinite is expressed. On an analog meter, the needle will not move), and the stator should be inspected or replaced. The stator could still be good in this case (if the voltages are good) and you caught it early, but it is definitely shorted. Refer to the service manual for removing the stator, and check for worn insulation, rubbed wires, or another short condition.

Test 3 - Regulator Rectifier Test PERFORM THIS TEST BEFORE RUNNING A BIKE AFTER STATOR REPLACEMENT!

This test is very important. If you've just replaced your stator, perform this test next, to make sure that it's safe to start the bike. Otherwise, your new stator may fail.

First, remove the regulator/rectifier from the bike, Noting the red, black, and white wire positions. On mine, I used a pencil and marked "R, B, W1, W2, W3" above each location a wire would be plugged into.

Set your regulator down and grab out your trusty meter, once again set to ohms. Zero the meter. Set to X1K resistance if the option is available to you.

Black probe to Black, Red probe to White 1
Black probe to Black, Red probe to White 2
Black probe to Black, Red probe to White 3
Note the readings.

Repeat the tests, this time reversing the probes (Red to black, black to white)
Repeat the tests one more time, but this time, in places where you tested using the black pin you noted, use the red. You should have 12 readings noted.

If your rectifier is working properly, you are looking for low resistance in one direction, and infinite resistance in the opposite direction.

If you are unsure whether or not your regulator/rectifier is behaving as it should, ask! Running the bike with a bad reg/rect unit WILL damage the new Stator, better off to just not ride for an afternoon and ask the question before starting the engine. Do not start the engine or run the bike if either the stator or reg/rect has failed or is questionable. Coincidentally, running the bike with a bad stator can cause the reg/rect unit to fail. If you believe your stator is failing, ride it home, shut it down, and perform the tests. Do not ride until the offending parts have been replaced!

If you get the correct readings, re-check the stator for a short-to-ground, plug the regulator back in, and start the bike. Once the bike is running, switch your meter to DC Volts, and rev the bike. Between idle and 5k rpms, you should have readings around the 14v mark the entire time. Mine are between 13.6-14.1. It should never be well below 13v (like 12.3 or something like that), and should not exceed 15v. If it does, your regulator/rectifier needs to be replaced (The 'regulator' part is not functioning correctly). Shut the bike off, and do not run the engine until the regulator/rectifier is replaced.

Hope this can be of some help! Just know that this is 99% from Sfair, be sure to give him a big THANK YOU for all the help he does in this forum and the information he gave for us here!

Stator Removal Video:

Happened upon this YouTube video which details the removal of the OEM Stator quite well. https://www.youtube.com/watch?v=P1nSvWdnN3k
 

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Discussion Starter #3
I'd like to sticky this thread, but I want Sfair's approval first. I'd also like any comments/questions so we can get it cleaned up before stickied!
 

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Just one correction. It would be possible to overload the stator with too many accessories which "may" cause some issues, but you probably would end up with a dead battery first.
Say you installed a light bar and you want to check that your charging system can handle it:

1. Run engine up the the speed that it normally turns at 30mph, 2500??? Use your ear as a guess if you have no tach.
2. Take a voltage reading across the battery.
3. Turn on the light bar and take another reading.
4. If the output drops more than a few tenths of a volt, then the alternator may not keep up under normal driving conditions. If it drops to 12v, then you have problems.
 

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Perfect!! Placing this as a sticky will be great and easy information to find. Kudos for a great write up... :good:
 

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Discussion Starter #8
Please include the infamous water in the reg/rec plug that, mixed with dirt, will provide a path to ground for the incoming 50+VAC from the stator.
You'll note that I did, but even though that's a popular 'reason' if you will, Sfair has told me he doesn't think that's a likely situation. He explained it in another thread. When it comes to this stuff, he is the absolute authority around here. As I understand it he works or has worked on equipment like that for a living and REALLY knows his stuff. So, if he says the water and dirt doesn't cause the stator failures, I believe him.

That said, I do think there is a correlation between the instances of inclement weather riding and stator failure, and I don't believe in coincedences, BUT, I'm inclined to believe whatever Sfair says.
 

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Discussion Starter #9
Thread has been stucked!

Sfair, I included an edit based on what you said regarding load. I'll leave this open for discussions regarding the stator. May include some notable comments in the second post, so just consider this your 'be warned' that after this post I may take something you say and copy and paste it into my second post there, if it adds value to the write-up (so don't sue me haha)
 

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You'll note that I did, but even though that's a popular 'reason' if you will, Sfair has told me he doesn't think that's a likely situation. He explained it in another thread. When it comes to this stuff, he is the absolute authority around here. As I understand it he works or has worked on equipment like that for a living and REALLY knows his stuff. So, if he says the water and dirt doesn't cause the stator failures, I believe him.

That said, I do think there is a correlation between the instances of inclement weather riding and stator failure, and I don't believe in coincedences, BUT, I'm inclined to believe whatever Sfair says.
In general when you mix water and minerals (dirt) and allow it to bridge a power source, be it across three phases or to ground, you will develop tracking and eventual failure of one or more components. This is not exclusive to motorcycles but is true across the spectrum of electrical installations. Fifty+ VAC phase to phase is not to be taken lightly and a clean environment is essential.
 

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Discussion Starter #11
In general when you mix water and minerals (dirt) and allow it to bridge a power source, be it across three phases or to ground, you will develop tracking and eventual failure of one or more components. This is not exclusive to motorcycles but is true across the spectrum of electrical installations. Fifty+ VAC phase to phase is not to be taken lightly and a clean environment is essential.
What precautions would you suggest taking to help ensure it's clean and dry?
 

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What precautions would you suggest taking to help ensure it's clean and dry?
Unplug the connector and spray both the reg/rec plug end and the wire loom connector with contact cleaner followed by a shot of air from your compressor. Inspect to be sure any contaminants are removed. Coat the spade ends with dielectric grease and dab the female ends with a smear too. The frequency depends on how and where the bike is ridden. If it's ridden in the rain often as a commuter bike would be or if the bike is washed at a car wash where they use a high pressure hose then the connection should be opened and inspected more often. The problem is that Kawasaki should have installed a plug end that would remain water tight even in the worst of conditions since they placed it right in line with the front tire and low enough to get deluged when ridden thru standing water.
 

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Discussion Starter #13
Unplug the connector and spray both the reg/rec plug end and the wire loom connector with contact cleaner followed by a shot of air from your compressor. Inspect to be sure any contaminants are removed. Coat the spade ends with dielectric grease and dab the female ends with a smear too. The frequency depends on how and where the bike is ridden. If it's ridden in the rain often as a commuter bike would be or if the bike is washed at a car wash where they use a high pressure hose then the connection should be opened and inspected more often. The problem is that Kawasaki should have installed a plug end that would remain water tight even in the worst of conditions since they placed it right in line with the front tire and low enough to get deluged when ridden thru standing water.
I don't TRY to ride in the rain but it does happen.

I'm still curious about the issue, but it can't hurt to take those simple precautions.

I've got a can of aerosol spray di electric grease. Will that work, or should I get the good'n'goopy stuff?
 

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In general when you mix water and minerals (dirt) and allow it to bridge a power source, be it across three phases or to ground, you will develop tracking and eventual failure of one or more components. This is not exclusive to motorcycles but is true across the spectrum of electrical installations. Fifty+ VAC phase to phase is not to be taken lightly and a clean environment is essential.
I Agree with you 100%, but in this case, the bridge must be capable of carrying more current than the stator winding itself, 10,15,20 amps for a time.
This is not like a utility transformer that can form a track from air pollution, the transformer arcs over, the track is blasted away or blows a fuse. It would have to remain in place carrying enough current long enough to overheat the stator wires to the point of melting the insulation.
I have yet to see any gunk/water bridge in a connector that can carry that kind of current and survive. Usually the connector itself cannot take that kind of load. If it did, there would certainly be evidence (brown, blue, black or melted) of the high current flow in the connector.
Dirty connections can cause all kinds of problems...overheating of the connector, voltage drops, corrosion, etc., but in THIS situation, I do not believe that water in the connection is the "direct" cause of stator failure.
If it was, then clean connector stators should not fail.

Again, clean,tight and dry connections are a must! No arguement there.
 

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Discussion Starter #15
I Agree with you 100%, but in this case, the bridge must be capable of carrying more current than the stator winding itself, 10,15,20 amps for a time.
This is not like a utility transformer that can form a track from air pollution, the transformer arcs over, the track is blasted away or blows a fuse. It would have to remain in place carrying enough current long enough to overheat the stator wires to the point of melting the insulation.
I have yet to see any gunk/water bridge in a connector that can carry that kind of current and survive. Usually the connector itself cannot take that kind of load. If it did, there would certainly be evidence (brown, blue, black or melted) of the high current flow in the connector.
Dirty connections can cause all kinds of problems...overheating of the connector, voltage drops, corrosion, etc., but in THIS situation, I do not believe that water in the connection is the "direct" cause of stator failure.
If it was, then clean connector stators should not fail.

Again, clean,tight and dry connections are a must! No arguement there.
Not questioning you AT ALL Sfair, BUT, I still can't get over the fact that mine failed COMPLETELY the DAY AFTER getting caught in a rain storm and riding several hours in very severe rain, and I must have heard at least a dozen similar stories on this forum.

Is it possible (just trying to learn, if you tell me it's not then it's not, I guess I just have a hard time believing in coincidence lol) that repeated small shorts over a period of time could damage the stator but not the connector? That is to say, the stator failure was not from one single wet-weather event, but the culmination of damage from several over a period of time? I took me 5 hours (riding time, several stops made it longer, give or take) through very, very severe weather to get home. I know that connector was SWIMMING. There were periods of time where I was idle-walking it through deep puddles of water (no lectures on how dumb I was not to park the bike and catch a ride home LOL), where I know that for a couple seconds that connector must have been submerged... Either way, it was getting hammered hard.
 

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I Agree with you 100%, but in this case, the bridge must be capable of carrying more current than the stator winding itself, 10,15,20 amps for a time.
This is not like a utility transformer that can form a track from air pollution, the transformer arcs over, the track is blasted away or blows a fuse. It would have to remain in place carrying enough current long enough to overheat the stator wires to the point of melting the insulation.
I have yet to see any gunk/water bridge in a connector that can carry that kind of current and survive. Usually the connector itself cannot take that kind of load. If it did, there would certainly be evidence (brown, blue, black or melted) of the high current flow in the connector.
Dirty connections can cause all kinds of problems...overheating of the connector, voltage drops, corrosion, etc., but in THIS situation, I do not believe that water in the connection is the "direct" cause of stator failure.
If it was, then clean connector stators should not fail.

Again, clean,tight and dry connections are a must! No arguement there.
I won't argue the point as no one I know has ever shorted out the stator windings coming into the reg/rec just to see what would happen. I do remember a couple of years ago reading posts on this forum of owners unplugging their reg/rec and finding dirty water running out. No way this is a good thing and flagging this weak connection as a periodic maintenance item can do no harm and just maybe will add to the life of the charging components.
 

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I won't argue the point as no one I know has ever shorted out the stator windings coming into the reg/rec just to see what would happen.
The regulator will sometimes do it for you and the result is black windings, burned connectors, etc.
"There are strange things done 'neath the midnight sun", so I cannot "guarantee" that rain will not cause a problem, but the evidence and science do not seem to support that.
So the question is which is first... black wires then short to ground, or short to ground then black wires?
 

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Discussion Starter #18
The regulator will sometimes do it for you and the result is black windings, burned connectors, etc.
"There are strange things done 'neath the midnight sun", so I cannot "guarantee" that rain will not cause a problem, but the evidence and science do not seem to support that.
So the question is which is first... black wires then short to ground, or short to ground then black wires?
The latter is kind of what I'm leaning to. My stator was worn physically (as I described in the earlier thread) which was obviously a cause for a short-to-ground. It seems to me like, that already failing (unbeknownst to me) stator, along with lots of water in the regulator, caused it to finally jump ship. Maybe? Or maybe the water had nothing to do with it and it's just coincedence.

Sojourner, when I unplugged my regulator to replace my stator (stator failed, ordered a new one the day after it failed, came in within a couple of days, so in other words this was just after the rain storm), I had probably a teaspoon and a half of muddy water pour out. It definitely gets wet.

Will electrical tap work near that connection? Several inches BEHIND the regulator plug is plastic insulation. I was thinking about tightly wrapping waterproof electrical tape from that insulation, to and over the regulator plug, and then over the shroud of the regulator/rectifier, along with the di-electric grease as you suggested. I figured it would make a nice waterproof seal and couldn't look worse than the 6 colored wires coming out of it now... If I need to unplug it removing electrical tape is pretty easy, haha. I also considered heat shrink tubing from the insulation, to the regulator plug, then electrical tape to cover the regulator plug and over the regulator itself.

I noticed that on most bikes, it seems like the regulator is mounted with the plug facing DOWNWARD, but open like ours. That seems to make a lot more sense (it's also mounted higher on air cooled bikes). Because water can't STAY in the plug, it'll drain out.

Kawasaki, if you're reading this, how about you fix it instead of making us :D. I wonder if it has been fixed, I know the issue dominated the '06, '07, '08 models, but... that's kinda like saying a 2012 Ford F-150 is more reliable than a 1991 F-150 because nobody has ever had a catastrophic engine failure on a 2012 F-150 but they have on a '91. In other words, those newer bikes might not have enough life on them to have a stator failure. Maybe in 6 years we will see the same pattern of threads about '12 900's failing?
 

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Re: Stator

I would like to say thank you for the heads up. So far, Knock on wood, I haven't had any problems. I have a 2009 Kawasaki Vulcan 900 Custom. I have almost 6000 miles on her.

Robert aka Unk.
 

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Has anybody tried/found a good place for relocating the regulator for prevention of this water buildup? I haven't thought about it, but this thread will definitely make me look.
 
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