Electrical problem? Don't think it's stator or R/R

[Anonymous]

I have an '81 850GL. Bought three years ago and promptly replaced the dead stator and R/R with Electrex units. Bike ran well for a time, but eventually started doing strange things.

Riding along it would start to 'miss' or feel like it was starving for fuel. I could usually accellerate out of it which would appear to blow the fuel starvation theory out of the water.

Bike has been garaged for the majority of the last two years, due in part to the unreliability factor, plus snow, no windshield... other reasons.. Would sometimes fire it up for a spin around town, and it would be fine for a while, then start the same symptoms again, which led to it being parked again.

We've since moved to Las Vegas, Nevada, land of year-round riding.
So I want to get it up and running.

BUT now the problem is much worse. Ran absolutely FINE for about 15 minutes. Started fine, ran fine. It started the 'miss' thing again. Sounded like it was running on three cylinders, sounded really 'throaty'. Twisting the throttle gradually went from being partially effective to NOT effective at all.

While I was sitting at some lights about 4 miles from home, barely keeping it going in neutral, I pulled #1 spark lead off the plug, and that made no difference at all. I was expecting to get a sharp zap from it, but it was more of a mild tingle. (Sort of like putting your tongue on a 9v battery)

I pulled all the plugs yesterday, all but #1 were in great shape. #1 looked oily. Not drenched in oil, but if you run your finger over it, it left a black smudge.

Coming closer to home, with the throttle almost wide open to keep going, it briefly accellerated for a second.... fell back.... accellerated..... fell back, and once again, then stayed back at barely going. Finally it totally crapped out about 1/3 mile from home and I walked it back.

I've just come back up from the garage. Plenty of fuel in the inline filter. Cranks like a sumbitch. tries to start. idled really rough for a few seconds then died. Throttle was no/little help.

I'm Stumped

If I had my multimeter I'd check the R/R but that's in my truck and the wife has that today. Not sure if that'd be a help anyway, as the bike is supposed to be running when you check that, isn't it?

Cheers

Chris In Vegas

[earlfor]

If it turns over well when the starter button is pressed, then the battery is well charged and consequently the charging system is working as it should.
If it is only one cylinder that is dropping out, then it is not a coil or ignitor problem as either of those would cause the loss of two cylinders. It isnt a voltage loss to either coil as that would also cause the loss of two cylinders.

I would check resistance on the coil secondary to see if the resistance between the plug caps is correct. I suspect it will not be between the 30K to 50K range it should be in. Probably you will have to replace one of the plug caps. Its possible you have a plug cap that is heating up and shorting out.

Earl

[Anonymous]

Thanks for the reply Earl.

What/where is the coil secondary?

I can do very basic stuff with a multimeter, if I have instructions, but I'm not sure how to check for resistance.

If one plug cap is shorting out, would that cause the engine to not start/run? I may go test that by pulling #1 plug lead off the sparkplug and isolate it and see what happens.

Chris

[Anonymous]

Ok, Just came back upstairs.

Bike fired up like a champ. No problem, you wouldn't think that a couple hours ago I was pushing it along the road.

Idled nicely..... Revved up smoothly.

Could it be heat related? Something expanding in the heat and losing contact? not sure what though. any ideas?

Arrrrghhhhh

Chris

[IanFrancisco]

Coils can get weak as they get hot, but like the previous post said, it would affect two cylinders not just one. It could be a defective plug, cap or plug wire which can easily be tested by swapping to another cyl. If one of those three were bad the problem would move to the new cyl.

[Anonymous]

Just pulled the sparkplugs again. 2 & 3 look great, but 1 & 4 are the same, black residue. not sooty or oily. I'm guessing that it's just unburned fuel.

It works when engine is cool, but when it gets hot, it starts playing up?

Wife is home, so I hope my multimeter is in the glovebox where I thought I left it. How do I check the coils with it?

Thanks

Chris

[earlfor]

Ahhhh, you just changed the game from Scrabble to poker. LOL Having the 1 and 4 plugs black is an ignition side/half. That would likely rule out a single spark plug cap as being the fault as when you first indicated it was only one plug fouling. The possibilities now are faulty crankshaft trigger, a faulty ignitor box, or a faulty coil, or bad connection to one coil. The first thing I would do is remove the gas tank and clean the wire connectors to the terminals on both coils. (each coil has two terminals on its end, One terminal is 12v+ input/power supply. The other terminal on the coil is 12v+ output. These two terminals are the "primaries".

The left coil fires cylinders 1 and 4. The right coil fires cylinders 2 and 3.

Disconnect the orange/white wire from its terminal on the left coil. That wire is the 12v + power supply for the coil. With a multimeter, check the voltage on the orange/white wire, with the wire disconnected from the coil and with the ignition switch turned on. It should read close to the same as voltage at the battery terminals.

Next, check the primary resistance on the left coil. Set your meter to the ohm scale (the symbol looks like a little horseshoe) Set the meter to the 200 scale. You already have removed the orange/white wire from the coil.
Now, remove the white wire from the other terminal on the coil. Place the meter probes on the two terminals. The meter should show 3 ohms. (average will be somewhere between 3 and about 4.5)

Now, check the secondary resistance. (ignition off) Set the meter to the ohm scale 200K. Place one meter probe into the #1 spark plug cap (spark plug removed) and the other probe into the #4 plug cap. Be sure to make contact with the metal clip inside the cap. The reading should be between 30K and 50K ohms.

I am guessing heat is causing an increase in resistance and you are losing ignition. When the component cools down, it obviously works normally again. I would expect to see normal readings if the above checks are made when the engine is running normally. I would make these checks and if all seems well, I would ride the bike up and down in front of my house until it quit. I would carry the meter with me and whatever tools I needed to remove the tank to recheck the coil resistances. Unfortunately, its a case of needing to find the problem when the bike isnt running. :-)
If the bike quits running and the coils still have within specs resistances and voltage supply, then it is unlikely the coils are the problem.

If that is the case, then the next component up the line is the ignitor box and it would be suspect that it has nearly burned out a resistor on the 1,4 side of the ignition.

Earl

Just pulled the sparkplugs again. 2 & 3 look great, but 1 & 4 are the same, black residue. not sooty or oily. I'm guessing that it's just unburned fuel.

It works when engine is cool, but when it gets hot, it starts playing up?

Wife is home, so I hope my multimeter is in the glovebox where I thought I left it. How do I check the coils with it?

Thanks

Chris

[Anonymous]

Just checked the coil secondary.

with Ignition OFF
Coil running cyls 1&4 read 34
Coil running cyls 2&3 read 78

with Ignition ON
Coil running cyls 1&4 read anywhere between 24-55. constant fluctuation, would not settle.
Coil running cyls 2&3 read 31

What is the coil primary? Is that the two wires going into the coil from the wire harness?

Is the secondary test supposed to be performed while Ignition is ON? Do these results tell me that the coil running 1 & 4 is suspect?

Thanks

Chris

[Anonymous]

I guess our messages crossed, or you sent yours while I was still downstairs fiddling.

The 'primary' wires on my coils appear to be hardwired/glued into the coil, no terminal post. It has one wire going into either end of the coil 'body', both hardwired/glued. Maybe under the glue it is a terminal post. I'll have to pry the glue/crud away to check.

I figured I'd have to take my gear with me and ride it around nearby until it crapped out again... Wife wants some attention, so I guess I'll have to wait until later to try that..

On my way to check primaries.... I'll just disconnect the harness connector and that'll give me access to the wiring

Chris

[earlfor]

First, what was the left coil DC voltage supply on the orange/white wire when the wire was disconnected from the coil and the ignition switched on?
(it should be between 12.5 and 13 volts) ??????


Now, with the ignition switched back off and both wires disconnected from the left coil, (cylinder 1,4 coil) you say a reading of 34 ohms? Do you mean 3.4?

Disconnecting the wires from the terminals on the right coil (2,3 side) you say you read 78? Do you mean 7.8? Even so, that cant be correct as the reading should be between 3 and 4 ohms. If it is your left coil that is faulty, then your 2,3 cylinders would be black.

Just to get the right picture in my mind, there is a way the factory wires the crank sensor and coils. Check to see if this is what you have.
On the right end of your crankshaft, there is a round 6 /12" plate covering the crank end. remove the three screws and cover plate. You will see a plate with two crank sensors mounted 180 deg apart. the sensor on the left side at 9 oclock will have a white wire going to it. The other end of that white wire goes through your wiring harness is the white wire that connects to the terminal on your left coil. check that you have that color on that coil terminal. the right crank sensor has a black wire and that black wire's other end should be connected to the terminal on the right coil. check that also. (it is not uncommon that someone has wired the coils correctly, but reversed their mounting position on the bike)

Checking the ohm resistance between the spark plug caps is done with the ignition off (coils unpowered) Lemme know what you get.

Earl

Just checked the coil secondary.

with Ignition OFF
Coil running cyls 1&4 read 34
Coil running cyls 2&3 read 78

with Ignition ON
Coil running cyls 1&4 read anywhere between 24-55. constant fluctuation, would not settle.
Coil running cyls 2&3 read 31

What is the coil primary? Is that the two wires going into the coil from the wire harness?

Is the secondary test supposed to be performed while Ignition is ON? Do these results tell me that the coil running 1 & 4 is suspect?

Thanks

Chris

[earlfor]

Works for me. :-)

E.

On my way to check primaries.... I'll just disconnect the harness connector and that'll give me access to the wiring

Chris

[Anonymous]

Ok, primary coil test results

Voltage at both coil wiring connectors was about 1 volt less than at battery so I guess I have some resistance between the coils and the battery. Is that a critical amount of volt drop?

Coil 1&4 read 4.7-4.9
Coil 2&3 read steady 4.8

I'll have to do this again after I take it for another ride I suppose.

[earlfor]

What was the voltage at the battery? Voltage at the coils? A 1 volt drop is terrible. My 1150 has about .03V drop (3/100v).

Both coils are between 3 and 5 ohms and according to the Factory manual, that is within spec.

What is the resistance between the plug caps?

E.

Ok, primary coil test results

Voltage at both coil wiring connectors was about 1 volt less than at battery so I guess I have some resistance between the coils and the battery. Is that a critical amount of volt drop?

Coil 1&4 read 4.7-4.9
Coil 2&3 read steady 4.8

I'll have to do this again after I take it for another ride I suppose.

[Anonymous]

Alright.. Back from my hot n sweaty breakdown ride. Lucky for me I managed to be only 100 feet away from the garage when it finally died totally.

Data is as follows:

Coil on 1&4:
Secondary resistance on 200k range was fluctuating wildly between 23-50
Battery was showing 12.2 v
Coil was getting 11.48 v at the connector
Coil Primary resistance at 200 range (not 200k) was 5.1 ohms

Coil on 2&3
Secondary resistance on 200k range was steady at 30
Battery had dropped to 12.07 v
Coil was getting 10.12 v at the connector
Coil Primary resistance at 200 range was 5.5 ohms

The pickup plate on the right crank end had a Blue wire going to left pickup, a Green wire going to right pickup and a red wire connecting the two together. I was unable to test resistance between them as the wires went directly into the rubber part of the pickups.

I hope it's not the CDI/ignitor unit or something

Chris

[Billy Ricks]

To test the coils put one probe of the multitester on each of the terminals on the primary side of the coil. Primary side is the side that gets signal from the igniter. You should get 3-5 ohms. Check the secondary windings by placing one probe into each of the plug wires coming from one coil. Those would be 2 & 3 from one coil and 1 & 4 for the other. You should get 30-50,000 ohms for stock coils and 15-20,000 for aftermarket. The test is done with the ignition off.