'80 XS11 LG "No Spark"

[3Phase]

Gene,

The 1980G Standard electrical system is almost identical to your 1980LG Midnight Special but the differences may confuse things so here's a link to a color wiring diagram for your bike:-
1980 XS1100SG/LG and 1981 XS1100SH/LH


For the no-start problem: have you checked the pick-up coils/connectors? They should both be at about 720 Ohms. If they're much higher, lower or open circuit, make sure the connectors at the TCI and behind the Fuse Block are clean, plugged in and tight. Suddenly losing spark to all four cylinders sounds to me like a loose connector, broken wires or a bad Ballast Resistor.

There is also an Ignition bypass wire from the Start Solenoid that bypasses the Ballast Resistor to feed a full 12V or more to the Ignition Coils when the starter is cranking the engine.

In trying to narrow down the low voltage causes I disconnected the Ignition Switch and put a jumper between the brown and red wires. I then got 12+ volts on several brown wire connections down from the switch.

You've found one of the more common dirty/corroded connections -- the Ignition Switch and its connector. I don't believe that's causing the 'no start' problem but the switch and connectors will have to be cleaned up or they'll slowly get worse, then the bike won't start and it'll run badly if it does.

But in order to get 12+ volts at the ign. circuit at the fuse area and also at the TCI I had to also unplug the connection from the Regulator/Rectifier to the Field Coil in the Alternator. This per the wiring diagram for a '80 XS11G vrs my bike which is a '80 XS11LG. These readings were all done "static".
When I switched back to using the actual Ign. Switch I was back to the voltage loss showing at about 11.4 volts. So it appears the the Ign. Switch has to come off and taken apart. I am not sure of the significance of the issue with having to unplug the Field Coil??? I have a spare Regulator/Rectifier from a '79 XS11F. It looks a bit different but the wires are the same. I have yet to try switching them out and wanted to get some comments prior to making a switch.

All of the Brown wires at the 'top' of the stock XS1100 Fuse Block and the Alternator Field Coil are spliced onto the one, single, Brown wire that comes down from the Ignition Switch.

As T.C. wrote, even with the Field Coil is connected a good battery should be able to keep the system voltage well over 12 Volts when the engine is not running. Charge the battery and unless it's a sealed or AGM battery, check the specific gravity in each cell.

What does the Reg/Rectifier and its connection to the Field Coil do? The other Reg/Rectifier connection goes to the Stator Coil in the Alternator.
Again, what do they do and is this normal?
gene

Well, the XS1100 Voltage Regulator/Rectifier does exactly the same thing any other Voltage Regulator/Rectifier. The XS1100 charging system is very similar to a Chrysler/Plymouth charging system.

The Rectifier section has a diode bridge to convert 3Phase AC current from the Alternator into DC current for charging the battery and running the rest of the vehicle electrical load. The XS1100 uses an external diode bridge in the Regulator/Rectifier and it's bolted to the frame under the fuel tank instead of inside of the alternator.

The Voltage Regulator section regulates the amount of current going through the Alternator Field Coil and keeps the Alternator output voltage somewhere between 12V DC and 14.5V DC.

.

[geneborg]

'80 XS11LG No Spark/Due Low Voltage "HELP"

I am still chasing my "no Spark" issues which I believe are a result of low voltage. I am getting a voltage drop of almost one volt in the ignition circuit. Three questions:
1) How does one check a "ballast resistor"?
2) I also note that when I unplug the connection between the regulator/rectifier and the field coil I get much less of a voltage drop. It stays in the mid 12 volt range. The field coil does take some power to light the headlight once the bike is started but should this drop the voltage as much as it does? Can the bike be started without this connection?
3) What is the minimum voltage to power the TCI?
gene in FL

[motoman]

I am still chasing my "no Spark" issues which I believe are a result of low voltage. I am getting a voltage drop of almost one volt in the ignition circuit. Three questions:
1) How does one check a "ballast resistor"?
2) I also note that when I unplug the connection between the regulator/rectifier and the field coil I get much less of a voltage drop. It stays in the mid 12 volt range. The field coil does take some power to light the headlight once the bike is started but should this drop the voltage as much as it does? Can the bike be started without this connection?
3) What is the minimum voltage to power the TCI?
gene in FL

Eliminating conponents out of system to solve low voltage issue is heading things in wrong direction, so ain't even goin there.
Key on, whatever that voltage is at battery needs to be the same at red coil input wires.....if it isn't, trace where the 'all important smoke' isn't flowing freely(resistance=bad connection).

[CaptonZap]

I am still chasing my "no Spark" issues which I believe are a result of low voltage. I am getting a voltage drop of almost one volt in the ignition circuit. Three questions:
1) How does one check a "ballast resistor"?
2) I also note that when I unplug the connection between the regulator/rectifier and the field coil I get much less of a voltage drop. It stays in the mid 12 volt range. The field coil does take some power to light the headlight once the bike is started but should this drop the voltage as much as it does? Can the bike be started without this connection?
3) What is the minimum voltage to power the TCI?
gene in FL

Set your multimeter on the lowest ohms scale, disconnect one or both sides of the ballast resistor, and measure the resistance from one end of the resistor to the other. It should be around 1.5 ohms. Most cheap meters are not real accurate at that scale, so anything close is good.
Unplug the three prong connector from the regulator, and see if the engine runs. If it does, consult the manual to get the check out procedure for the regulator. Sounds like it may be FUBARed.

CZ

[TopCatGr58]

Hey Gene,

As was stated, the BR is just a resistor, an ohmmeter should be able to test it, should have some resistance. As Steve pointed out in a recent thread, when it heats up its resistance usually increases. What you don't want to see is either NO resistance.."0" value which means direct path, no resistance....OR an infinite value which means OPEN circuit...no flow path at all...has been reported when B.R. dies, fractures and breaks continuity.

HOWEVER....the B.R. should not be a concern for a NO Spark NO Start scenario since it is bypassed during the starting function so a full 12 volts is sent directly to the coils for a stronger spark for easier starting. Only after the engine is running does the TCI route power THRU the B.R. for normal running.....at reduced voltage ~9 or so to prevent burning UP the coils, as well as providing the full 3 ohms that the TCI needs to see for the triggering function.

Surprisingly C.Z. did some formal bench testing on the TCI, and it continued to work at much lower voltages than suspected....however the coils seemed to drop out around the 10.5 volt level.....which doesn't make sense in a way since when running, the 1.5 ohm coils run using lower voltages since powered thru the B.R.? Go Figure?

There's a tip/mod about doing a direct powering of the coils from the battery, but that doesn't work for the earlier models that use the B.R., but if you were to put on aftermarket 3.0 coils, then you COULD wired them directly to the battery.

T.C.

[CaptonZap]

Hey Gene,


Surprisingly C.Z. did some formal bench testing on the TCI, and it continued to work at much lower voltages than suspected....however the coils seemed to drop out around the 10.5 volt level.....which doesn't make sense in a way since when running, the 1.5 ohm coils run using lower voltages since powered thru the B.R.? Go Figure?

T.C.

A little clarification, TC. When I ran that test, I didn't have the coils hooked to the output of the TCI, just a couple of lights. Every thing worked down to about 6 V. And if it ever got down to it, I think a guy could go a long way with a low battery by disconnecting all the lights, (except maybe the brake light), bypassing the ballast resister, push start, and go till it died.
The interesting thing about the TCI is that there is a Zener diode inside that regulates the operating voltage of the TCI to 6V, which is why I guess it quit below there.

CZ