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!)