Where is the voltage going?

[Barbarosa]

1980 SG that will start and idle, but fouls plugs quickly when ridden. Background info on what has been done is in another post. Carbs coming off again for new jets and fuel level recheck because jets were stamped 110 (not marked as Mikuni though) and the valves were replaced with KL. Want to clear this voltage problem before I crank it back up.
While working to get proper voltage readings at the fuse box I found that the system drops well over a volt when key is turned on. Figured out that the tail light draws .2v which is way less than it is actually losing. After isolating circuits during troubleshooting I discovered the voltage drop does not occur when the 2 wire connector to the alternator/stator is unplugged and key is switched on. Also, the plug is warm to the touch after key is on for a spell and it arcs when separated. Test at plug is 3.5 ohms and the 4 wire plug is 2 ohms across and infinite to ground. Don't remember the exact charge rate at the battery while running, but it was above 15v and the bike hasn’t run long enough to flatten the new battery. The headlight is inop while running as well.
The voltage drop and warm to the touch plug indicates a problem somewhere in the alternator/stator system to me and maybe someone else has encountered symptoms like this while chasing the smoke?

[natemoen]

Sounds like there is a major corrosion issue inside that plug. Time to open it up and either clean it or replace it if needed.

If that is the 4 wire plug that has 3 white and 1 yellow wire in it then the headlight problem may also be because of that plug. The yellow wire sends a signal to the headlight relay and tells the headlight to turn on.

[DiverRay]

He said the two wire plug. I'm thinking it may be a break-down on the coils inside the alt. But I DO agree, clean ALL connection on the bike, including ALL the ground connections.

[natemoen]

He said the two wire plug. I'm thinking it may be a break-down on the coils inside the alt. But I DO agree, clean ALL connection on the bike, including ALL the ground connections.

Yeah, but he also says something about a 4 wire plug after that.

Still comes down to cleaning the electrical system and replacing connectors if needed though.

[motoman]

1980 SG that will start and idle, but fouls plugs quickly when ridden. Background info on what has been done is in another post. Carbs coming off again for new jets and fuel level recheck because jets were stamped 110 (not marked as Mikuni though) and the valves were replaced with KL. Want to clear this voltage problem before I crank it back up.
While working to get proper voltage readings at the fuse box I found that the system drops well over a volt when key is turned on. Figured out that the tail light draws .2v which is way less than it is actually losing. After isolating circuits during troubleshooting I discovered the voltage drop does not occur when the 2 wire connector to the alternator/stator is unplugged and key is switched on. Also, the plug is warm to the touch after key is on for a spell and it arcs when separated. Test at plug is 3.5 ohms and the 4 wire plug is 2 ohms across and infinite to ground. Don't remember the exact charge rate at the battery while running, but it was above 15v and the bike hasn’t run long enough to flatten the new battery. The headlight is inop while running as well.
The voltage drop and warm to the touch plug indicates a problem somewhere in the alternator/stator system to me and maybe someone else has encountered symptoms like this while chasing the smoke?

Key on, check voltage at Run/Stop switch. A common location for voltage drop on these ole' 11's. I fneeded, remove kill switch,dis-asemble(careful not lose teeny internal spring), and drop ALL pieces in a small cup of EvaporRust for a few hours. Then remove, rinse with water and blow dry.

[3Phase]

Barbarosa,

The two-pole connector is for the alternator field coil and it should be what you've measured -- 3.5 Ohms. The connector will get warm and spark when you disconnect it if you leave the ignition switched on because the voltage regulator/rectifier doesn't know or care if the engine is running so it has the field coil maxed out while it tries to raise the system voltage. It'll stay that way until the voltage rises to the regulation point or the battery runs down.

The White wires from the stator should be 0.4 Ohms between each pair of wires.

Your 1980 SG doesn't use the Yellow wire from the alternator like a '78/'79 model, it has a diode in the wiring harness up by the headlight relay on one of the White wires. If the headlight won't come on after the engine starts you have to check the headlight relay and the diode.

New diodes are still available for roughly ten bucks:
3H5-81980-00-00 DIODE

If you replace the relay you have to find a used one from a 1980/1981 model or it won't work. It should be labeled 3H5 and new ones are no longer available:
3H5-81950-00-00 RELAY ASY ~$115


Yes you can bypass the headlight relay. In the headlight relay connector, put a jumper from the Red/Yellow wire to the Blue/Black wire and the headlight will come on immediately when the ignition switch is on.

.

[Barbarosa]

Understand how the plug would heat up and spark now. Still don't get how there is more than a volt being lost when the key is switched on though. The system does not lose voltage with the brown/green wires from the alternator unplugged, ONLY when connected. 11.3v plugged in 12.3v unplugged. If any switch or connector was not working there would not be 12.3v at the fuse panel. BTW, I now know where every connector and wire on this bike goes lol. Was hoping someone getting voltage up had the same experience and could relate. Will pull the alternator and see what's going on in there next. Might be something I won't need glasses to see.

[Barbarosa]

But I think before pulling the alternator will break down both plugs this time instead of just squirting them with cleaner.

[bikerphil]

It is your field coil drawing the extra volt, pretty sure that is normal. Try touching a thin piece of metal such as a feeler gauge to the outside alternator cover and it should attract with the key on. This requires voltage obviously.

[3Phase]

The alternator field coil is not fused and it gets power directly from the Brown wire (switched power) that runs from the Ignition switch down to the Fuse block.

Unless you're measuring the voltage at the battery, that voltage drop means that you have one or more bad contacts somewhere or your battery is toasted.

The possibilities include:
Battery Positive terminal to cable and solenoid
Main fuse
Harness to ignition switch connector
Ignition switch itself
All of the above

Use your volt meter and jumper across each component until you find the voltage drop.

For example:

Battery Positive terminal to solenoid - no voltage drop = cable and connection are good

Battery or solenoid to the Red wire going into the Ignition switch harness connector up in the headlight shell - a few millivolts = minor voltage drop across the Main fuse

Harness Ignition switch connector Red wire (in from battery) to Brown wire (out to Fuse block) - 1.5V drop = bad news

In this example you would have to check further to see if it's the harness connectors, the Ignition switch contacts or both that need to be cleaned to fix the voltage drop.

.

[AggiesaurusRex]

I have power going into the TCI but none coming out, am I doing something wrong? (Assume I know nothing)

[motoman]

I have power going into the TCI but none coming out, am I doing something wrong? (Assume I know nothing)

...not as of yet, but I suspect the initial batt. voltage is too low. Key on, batt voltage should be 12.5v minimum. Check across batt. poles with volt meter...key off for initial batt. voltage check, then with key on. Let us know here what that result is. This helps with what direction to diagnose.

[CaptonZap]

Hook your meter to the red with yellow wire on the TCI and ground, and turn the key on. You should see half a volt,+/-, less than the voltage at the battery. Push the start button, and you should see half a volt,+/-, less than the battery voltage at the white with red wire on the TCI. If the voltage is less than that, clean all the connectors on the bike, and dab a bit of silicon grease on the cleaned connectors before putting them together.
Be aware that the TCI turns off the voltage to the coils after 5-10 seconds if the engine doesn't turn over and ask for spark. This keeps the coils from burning out while you BS with your buds after turning on the ignition.

CZ

[AggiesaurusRex]

Okay, here is what I found. Voltage across my battery is 12.5, I tested everything right after turning the key each time.
My Red/Yellow is 0.02 after switching the key on, with the starter held it climbs to 8V.
My bottom Red/White (on bottom pin in TCI) which leads to my pickup coils reads 11.2, if I press the starter it dives down to 8 or 5.
My top Red/White (top pin) which leads to coils reads 0.1, if I press the starter and hold this jumps to 8V.
Anytime I press the starter I can here the solenoid click and my ground smokes. A ground smoking is indicative of too much resistance, right? I'll start breaking down everything and cleaning my connections. I also tested my voltage across my fuse box. I have 12.5 into in, 12.5 out to the key, 11.6 back in (this is a three-way branch, and 11.6 back through the other side but these fluctuate and almost seem to cycle starting at 8V and then climb to 11.6.

[DiverRay]

Anytime I press the starter I can here the solenoid click and my ground smokes

Houston we have a problem.....
You need to remove EVERY SINGLE GROUND WIRE, clean ALL connections, apply some anti seize or no-ox to the connectors and tighten them all up again. Be SURE you check the large wire from the frame to the engine. It runs from the bottom left rear to the frame. I put an extra 10 gauge wire from the engine to the battery negative as well. Also, if you have painted the engine and frame, you need to remove the paint/powder coating from the ground points so you get a good electrical connection.