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Electrical Trouble Shooting Results/Help **UPDATED INFORMATION***

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Hello again all,


I reran all my test today with a cheepo tach. Not the best but at least provides some consistency. The results on the stator made me go huh so I ran them three times and same results all three times. The Scenario is a repeat but the results are updated and expanded. I can do the fix, whatever it may be, but don't want to just start throwing parts at it to find out I am going in the wrong direction, or worse break the new parts. I really need some help interpreting the results here.



Went to start bike, Turns over but not enough to start. Put on charger. Next day started right up.

Went for ride. Approximately 10 minutes later started doing funky stuff, Radio cut on and off then entire audio shut itself off. Speedometer started jumping up and down weirding out. Blinkers not working. Turn back immediately got almost home got out of throttle bike died. Turned corner dumped clutch bike fired back up but really rough. Cranked throttle rpms way up smoothed out. Got home two blocks away. Of throttle to turn into drive died again. dumped clutch again few seconds rough running then total stop. Put back on charger next day started fine. Didn't ride, didn't want to risk it. Decided to troubleshoot thinking possible Battery. Rectifier or Stator.


Bike Electrical Status - No changes within a long time. Nothing added, nothing removed.


Troubleshooting Results:


Battery - 12 hour trickle 2A charge


After Charge - 12.46 VDC

At Idle - 11.85 VDC

At 2K RPM - 11.80 VDC

At 4K RPM - 11.80 VDC

After 5 Hours - 12.05 VDC


The after 5 hours test was done after the Stator test with the Rectifier unhooked


Rectifier -

Red Lead to Battery + Post / Black Lead to each Stator Post

1 - OL

2 - OL

3 - OL


Black Lead to Battery + Post / Red Lead to each Stator Post

1 - 0.477

2 - 0.474

3 - 0.466


Red Lead to Battery - Post / Black Lead to each Stator Post

1 - 0.471

2 - 0.477

3 - 0.478


Black Lead to Battery - Post / Red Lead to each Stator Post

1 - OL

2 - OL

3 - OL




Engine Off

OHMS Black Lead to Ground Wire / Red Lead to each Stator Wire

1 - OL

2 - OL

3 - OL


OHMS Stator Wire to Stator Wire @ 85F


1 to 2 - 0.6

1 to 3 - 0.6

2 to 3 - 0.6


Volts AC at Idle


1 to 2 - 25.5

1 to 3 - 27.0

2 to 3 - 26.5


Volts AC at 2000 rpm (with RPM meter)


1 to 2 - 75

1 to 3 - 102

2 to 3 - 79


Volts AC at 4000 rpm (with RPM meter)


1 to 2 - 115

1 to 3 - 150

2 to 3 - 112


Any ideas, thoughts or suggestions would be most welcomed. I will post this on the Forum as well but trust you know what you are doing and really hope you can give me some guidance here.


Thanks for any help here.

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I am not sure what the cause would be, but I am concerned that the charging voltage is to low. The service manual states that at 5000 RPM the charging voltage should be 14 VDC, you are showing less that 12. That would indicate maybe a bad regulator.

I am also concerned that there is an imbalance between the output of the three phases on the stator, I could not find anything published from Yamaha as to what the unregulated AC output voltage from the stator should be other than greater than 100 VAC, when I had RR problems on my 07 I seem to recall being told that AC output should be about 115 VAC, you are showing;

Volts AC at 4000 rpm (with RPM meter)


1 to 2 - 115

1 to 3 - 150

2 to 3 - 112


You have a 30 volt plus imbalance, that is 25%. I am not sure what in the stator would cause that but I am pretty certain it is not a good thing. Some of the stator repair/replace places on line, like RM Stator (https://www.rmstator.com/en_ww/) have a help line you can contact maybe they can help if you give them your findings.


My bet is that the imbalance in the AC output voltage from the stator has damaged the regulator/rectifier causing the low DC charging voltage.

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One of your stator windings has a couple of shorted windings, replace it!! That is why you have unequal voltages.


Also, take your battery to Auto Zone and have it load tested, at this point, it may be stressed...


Thanks Bob,


Looks like a clean system sweep is what it is going to end up being. Sigh. Guess I can't really complain after 112,000 miles.

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OK, time for me to TFU (Test For Understanding)...


You may be over testing, all you really need to do is first unplug the stator from the wiring harness located near the fuel pump, and arbitrarily label the 3 white wires A, B, and C. The stator end is the plug that heads down to the bottom of the bike, not the end that heads up to the wiring harness. Now, using an ohm meter on the highest scale, first read the resistance from each wire individually to ground. All 3 wires should read infinity ohms to ground! If there is NOT an open circuit to ground then one of your windings is shorted to ground and is defective! Next, with the ohm meter on a lower scale, read the resistance of all 3 combinations of wires, A to B, A to C, and B to C. All 3 readings should be almost equal, say within 1% of each other. If they are NOT almost equal, then one of the coils has a shorted turn or two and should be discarded! It is very important that these tests are done with the stator disconnected from the wiring harness!!! Of course, the bike should be turned off as well.


The above is known as static testing, which should be done first. The next step is to dynamically test the stator! With the stator still unplugged, switch your multitester to AC volts using the 200-volt scale. The output of a stator is AC volts, just like a generator because, in essence, that is exactly what it is! You are going to be measuring the voltage between the 3 combinations of wires just like you did when you measured the 3 coil resistances, NOT each wire to ground! Start the bike, and measure the voltages at idle. You should see some arbitrary voltage somewhere between 10 - 20 volts AC on each combination of wires, and they should all be approximately equal. Next, increase your RPM's to say 2000 RPMs. Your AC voltages should be much higher, say around 50 volts AC on each combination of wires, and should all be still pretty much equal. Increasing your RPMs to 3000 or higher should give you voltages closer to 100 volts AC. The point being, the voltages should all increase uniformly with increasing RPMs! It is also important that these readings are done with the stator disconnected from the system as there could be the possibility of a defective R/R dragging down the readings when connected!


I am going through this detailed information to make sure you, and any others reading this, are PROPERLY testing their stators operation! I would hate to see you condemn a stator if you did not test it the right way!


I also need to mention a somewhat uncommon but possible failure with stators, and that is a thermal problem where when cold, the varnish on the wires acts as an insulator, but when it heats up the varnish breaks down and shorts out the windings either to itself or to ground. The result being your stator tests fine when the bike is cold, and you go for a ride. Sometime later the varnish breaks down and you loose charging to the battery once the bike heats up! So, what you have to do is warm up the bike considerably and then while still warm, repeat the above testing!


OK, so if your stator is both statically and dynamically function properly, AND you have tested your battery with a load tester and you are absolutely sure it is good, then the last test is to determine if your Regulator/Rectifier is operating properly. With your multimeter now switched to DC volts this time, measure across the battery. You should see somewhere around 12.5 volts give or take. Now start the bike, and at idle you should see a little more voltage but not much. When you increase your RPM's the voltage should increase as well! At 2000 RPM you should see maybe 13.2 volts, give or take, and at higher RPM's you will see more voltage up to around 14.5 volts at high RPMs. There should be a point where with higher RPM's the voltage will no longer increase but remain the same regardless of how much more you increase the RPM's. This maximum voltage is what your regulator is set to regulate at, and no two regulators are exactly the same! I would discard any regulator that does not regulate at a minimum of 13.8 volts, and also discard it if it regulates anything higher than say 14.8 volts!


The last test of the R/R is to test if it is rectifying properly! What a rectifier does is converts the AC voltage coming from the Stator to a DC voltage that the bike's electrical system uses. Rectifiers can go bad or worse only half bad, where they will sort of convert to DC but will also have some AC riding along with it! To properly check this you need a device called an oscilloscope, but you can effectively test this with your multimeter turned back to AC volts on a lower scale and put it across the battery with the bike running at a higher RPM. You should see darn near zero volts AC at all times and all RPMs! You may see some tiny amount of AC voltage that could be coming from anywhere, but it should be below 0.1 volts AC! If you are seeing anything like 1 volt or more, there is a chance part of your rectifier section of your R/R is defective and should be replaced!!


Hope this helps you, and others out!!!

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You said: "The output of a stator is AC volts, just like a generator because, in essence, that is exactly what it is! "


I do believe, Sir, that you meant to say it's an alternator. A generator puts out DC volts, am alternator puts out AC volts.


Of course, my memory could be gone in this area as well! Grins...but that's what I remember from electricity 101...

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Well, yes, technically you are right! I was thinking/associating with a power plant where a turbine drives a shaft which uses a 3 phase winding to "Generate" AC power...




However, with Automobiles, the old and extinct Generators had a DC output via an assembly known as the "slip ring" assembly, but even then, the primary voltage generated by the coil and magnet configuration is AC before it is converted to DC. Alternators used a "diode bridge" built into the AC Generator to convert it into DC instead of the slip ring on alternators. The main principle is if you rotate a coil within a magnet, or rotate the magnet around a fixed coil, AC voltage is "Generated."

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I 100% agree with BongoBobby.....you have shorted stator turns. I had a Venture stator that was intermittent and I used another test to show that my problem was the stator having intermittent shorted turns. Disconnect the R/R and take 3 115VAC lamp sockets and 3 identical 75 watt 115 V incandescent light bulbs. Connect the 3 lamp sockets to the stator leads by connecting each lamp socket lead to one of the stator leads. When you're finished connecting them you will have 2 socket leads to each stator lead. Install the light bulbs and start the bike. At idle, the lamps will glow dimly but at about 3,000 RPM they get pretty bright. Each lamp should look identical to the other two. With my intermittent stator, I could see two of the lamps getting brighter and dimmer without changing the engine speed. If you do this test, your lamps will show different brightness, but won't change like mine did because yours isn't intermittent.

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