Submitted by BongoBobNY

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


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!!!