Unfortunately, the stator in my 1125CR bit the big one the other day. What’s weird is that it went from working fine to a state of total failure within about 25 minutes. Typically, an issue will appear in one phase of the three phase stator, and just drop it down to either 1 or 2 functioning phases - meaning you won’t have full charging capacity, but you will still have something.
With mine, it died much quicker.
Let’s start with some back story on the charging system of these bikes. The stators in the 2009 and 2010 models have an increased output (which means larger thermal load), as well as very little in the way of airflow, oil spray, or oil bath to help keep things cool. In an effort to prevent the stator from burning out, these bikes were recalled to have a harness added between the stator and the regulator. Under certain thermal and engine conditions, one leg of the stator is cut out, bringing the system to 1/3 capacity. Given this knowledge, it isn’t alarming to see voltages in the 12 volt range while sitting still for a long amount of time. Everything gets hot, the fans start running full blast, and charging system capacity is cut. This new harness hasn’t been successful in completely cutting out stator failure, however. Various efforts have been made to solve this issue, including installing different voltage regulators, modified rotors to promote airflow or spray oil directly on the stator, or even the installation of the lower output 2008 charging system. I’ve personally installed an oil spraying rotor, and am considering installing a new regulator and removing the stator control harness.
But I digress… Let’s go back to the stator failure itself. Everything was fine when I left for work that morning - the charging system was running at around 14.1 volts at idle. When I left work in the afternoon to head home, I got caught at a traffic light, as normally happens. I usually flip to the screen on my instrument cluster that displays system voltage - to make sure I’ve got power, and to give myself plenty of warning if the harness cuts the stator output. However, I noticed that the system was only running at around 12.7 volts or so, which is unusually low. I figured that the relay in the stator harness may be bad, as voltage returned to the 14 volt range when I was moving. The harness should not have been activated at that point, as the motor was still relatively cool. After that instance of traffic, everything seemed fine, so I flipped off the voltage display and drove home. Somewhere on my ride home, the stator suffered a complete failure; I did not notice the failure though, as I got home well before the battery drained far enough to affect the bike.
Two days later, I pulled the bike back out to take it to work. While starting it, I noticed it cranking a little slower than normal, but the bike started fine. However, my GPS/XM and TPMS both remained off. For the ECM to activate accessories, voltage has to go higher than 12.9 volts after starting the bike, so seeing the accessories not come on was alarming. I saw that system voltage was around 11.9 volts, so I put the bike back in the garage and put the battery tender on to refill the battery.
After work, I did some troubleshooting. I bypassed the stator control harness in case that was the problem, to no avail. I checked the AC output of the stator, and all 3 phases were reading abnormally low. Normal voltages are in the range of 20 VAC at idle, and 45-55 VAC at ~3k RPM. My readings were around 2 VAC at idle, and 3.5 or so VAC at ~3k RPM. None of the stator legs were shorted to ground, and between each leg was showing some resistance (as it should), so the stator only failed the output test.
I pulled the bike apart and removed the stator. In taking it apart, it was obvious that the rotor was fine, and hadn’t lost its magnetism. One of the poles on the stator looked especially charred, but other than that, nothing smelled burnt or anything.
My final test was one I made up myself. I hooked 12VDC across each of the phases of the stator. I limited current to 30 amps during this test, which is below the typical operating power of the stator at anything much above idle. The stator didn’t make it close to 30 amps before the charred pole started arcing and smoking. Similar results no matter which phase the power was applied on, and it happened in the same area. This happened instantly upon application of power, so it wasn’t damaged caused by my testing. The failure area was where the wires for two of the phases cross between two of the poles, so my best guess is that something got hot enough to burn the insulation off the windings, and cause a short.
If you’re still reading this, then kudos to you. Here’s some stator pr0n to reward you - pictures of the failed stator. The area circled in yellow in the last picture is where the failure occurred. At any rate, it’s time to install a new stator. I’m optimistic that the oil spraying rotor will prevent a new stator from burning up, and that the reason for this failure was that the stator was damaged heavily already.