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Charging System/Tachometer
Tips and Troubleshooting
by Gary LaPook; From the XS11 list on 7/16/00
Rick Z. wrote:
I have a 1980 XS1100 special. My problem is that when I start the machine, if the tach doesn't work, then the headlight won't work and the alternator won't charge. This problem is intermittent, it comes and goes. Sometimes the tach will work when the 4-way flashers light. Also my turn signals do not work at al.
The reason for the first two symptoms is the same. The tach gets its input directly from one winding of the alternator so, if the alternator isn't working, then the tach won't work either.
In fact, this feature provides a warning of alternator failure and this should always be suspected if the tach stops working. If you are away from home it is a good idea to pull the headlight fuse to lessen battery drain and try to get home on the remaining juice in the battery.
The reason the headlight won't come on is that the headlight relay gets it control input directly from the alternator also. After the bike starts (and the alternator starts alternating) the current goes to the headlight relay and trips it to the ON position. Then it "latches" into the on position and stays on until you turn the ignition switch off.
Troubleshooting the Alternator
To gain easy access to the alternator, take out the two screws that hold the fuse block in place and then move it over to the side so you can get access to the space behind it.
You will find two wiring connector blocks one with three white wires, which are the output wires from the alternator, and the other block has a green and a brown wire.
Open the connector blocks and clean the connectors. This in itself may cure your problem; it did mine.
With an ohmmeter measure the resistance between each white wire. These wires control the stator. It should be 0.4 ohms +/- 10%.
The resistance between the brown and green wires should be 3.5 ohms +/- 10%. These are the wires that go to the field coil of the alternator. The brown wire carries current from the battery and the green wire goes to the voltage regulator.
With the connectors back together turn the ignition on and you should measure about 12 volts between the brown wire and the bike frame and it should be less than 1.8 volts on the green wire.
Then start the bike and as you rev the engine the green voltage should go up to 9~11 volts if the regulator is working properly. If you measure battery volts on the green wire with the ignition on and engine not running then the regulator is not working and the alternator will not put out any current.
To get home you can connect the green wire from the alternator to the frame and this will get the alternator to put out current but the voltage will not be regulated and may get too high but you can check this with a meter. If you can get about a 5 ohm 10 watt resister from Radio Shack you can but this in the wire between the green wire and the frame which should help keep the volts from going too high.
I have also heard of using a taillight bulb in the place of the resistor.
Tips and Troubleshooting
by Gary LaPook; From the XS11 list on 7/16/00
Rick Z. wrote:
I have a 1980 XS1100 special. My problem is that when I start the machine, if the tach doesn't work, then the headlight won't work and the alternator won't charge. This problem is intermittent, it comes and goes. Sometimes the tach will work when the 4-way flashers light. Also my turn signals do not work at al.
The reason for the first two symptoms is the same. The tach gets its input directly from one winding of the alternator so, if the alternator isn't working, then the tach won't work either.
In fact, this feature provides a warning of alternator failure and this should always be suspected if the tach stops working. If you are away from home it is a good idea to pull the headlight fuse to lessen battery drain and try to get home on the remaining juice in the battery.
The reason the headlight won't come on is that the headlight relay gets it control input directly from the alternator also. After the bike starts (and the alternator starts alternating) the current goes to the headlight relay and trips it to the ON position. Then it "latches" into the on position and stays on until you turn the ignition switch off.
Troubleshooting the Alternator
To gain easy access to the alternator, take out the two screws that hold the fuse block in place and then move it over to the side so you can get access to the space behind it.
You will find two wiring connector blocks one with three white wires, which are the output wires from the alternator, and the other block has a green and a brown wire.
Open the connector blocks and clean the connectors. This in itself may cure your problem; it did mine.
With an ohmmeter measure the resistance between each white wire. These wires control the stator. It should be 0.4 ohms +/- 10%.
The resistance between the brown and green wires should be 3.5 ohms +/- 10%. These are the wires that go to the field coil of the alternator. The brown wire carries current from the battery and the green wire goes to the voltage regulator.
With the connectors back together turn the ignition on and you should measure about 12 volts between the brown wire and the bike frame and it should be less than 1.8 volts on the green wire.
Then start the bike and as you rev the engine the green voltage should go up to 9~11 volts if the regulator is working properly. If you measure battery volts on the green wire with the ignition on and engine not running then the regulator is not working and the alternator will not put out any current.
To get home you can connect the green wire from the alternator to the frame and this will get the alternator to put out current but the voltage will not be regulated and may get too high but you can check this with a meter. If you can get about a 5 ohm 10 watt resister from Radio Shack you can but this in the wire between the green wire and the frame which should help keep the volts from going too high.
I have also heard of using a taillight bulb in the place of the resistor.