Elusive electrical problems (solved)

Then I'm back at the TCI's door step, yes I was being lazy. double check the pickups and especially the wire bundle under the LH cover, lots of problems have been found there, quite recently 5twins found the new to him XS had a badly worn wire in there, boom cheap bike was a runner. Happened to me also.
 
The bad wires I found weren't merely worn, they were cut by the chain running against them. The P.O. didn't route the wiring loom from the alternator correctly. He didn't trap it under the shift shaft with the shaft protector like he should have. That side lined the bike for the past 12 years. I guess he always meant to fix it eventually but he never did. He got another bike and just moved on.
 
Today I took the day off to work on the bike. I'm doing some check ups before I do another test ride. I just checked the TCI pick resistance and am not sure if they are ok.

Black-orange : 700ohm
Black-grey: 700ohm
Orange-Grey: 1400ohm

The manual states "check pick up coil resistance, should be 700ohm. Is mine ok? They didn't state which leads to measure.

Secondly I added a voltmeter to the handlebar to see the battery voltage while riding.
 
Those readings are good. Your pick has two windings inside. They have a central ground connection, the black wire, with two hot sides. the grey and orange. The black/orange is one side. Black/grey is the is the other, The orange/grey is both.
Leo
 
Thanks Leo, looks like the pick up coil is OK.

I just went for a testride (and walk back home). Although its mid summer it was worth it. Got a lot of data and a bit of a tan. I rode for exactly 7 km and its pretty hot at 28°C (83°F). This is what I checked or found:

  • I installed a voltmeter to check the voltage of the bike while running. During the ride I stayed in the green, so nothing above 15V or below 12V.
VOM meter.JPG


  • After the 7 kms the bike started to pop in the exhaust a bit, especially with the throttle closed. This after a few seconds the bike feels down on power and this gets worse until it stops/stalls. This is the same failure mode I have had before.
  • Immediately after coming to a standstill I check if there was fuel in the filter. Its a see through type and there was fuel. Then i opened the gascap and did not hear and sounds indicating a vacuum was broken (tank vent).
  • I brought a spare spark plug and used it to check for sparks. First I tried the RHS lead, no spark. Then I switched to the LHS and while kicking I could see a few sparks. However after 3 more kicks they were gone.
  • Secondary coil winding resistance after stopping: 27k Ohm. before testride while cold: 24k ohm.
  • I measured resistance on primary side of the coil. between the two primary leads (red and orange) around 2,9 ohm. pretty similar to the cold measurement.
  • secondly i measured the resistance between the primary leads and ground. Here i found something weird: I would measure around 7 ohms between the red (hot) wire to the coil and ground. and around 10 ohm between the orange (signal) and the ground....
coil weerstand.JPG


  • at this same connector I measured the pick up coil resistance again. both were 700 ohm while cold, after the test ride they are both around 850 ohm.
  • I brought a second (tested) TCI with me. Tried it, nothing happened.
2de tci.JPG


  • Checked the battery voltage: ignition off 12.7V. Ignition on 12.4V.
  • with the ignition on I measured the voltage going to the ignition coil (red). I measured around 12.15 V.
voeding coil.JPG


after that is was just a walk home
walk home.JPG


what do you guys think??

I find the 7-10 ohm resistance between the primary leads of the coil and ground pretty weird. Besides that I dont think its a fuel problem. Since i first saw a few sparks and then nothing...
 
See if the bike starts/runs normally again once it cools down. That can often indicate a bad coil. They break down and fail when they get hot, work fine cold.
 
I find the 7-10 ohm resistance between the primary leads of the coil and ground pretty weird.
Yup... it appears that the primary insulation is breaking down when it gets hot. Sounds like a bad coil.
 
boom cheap bike was a runner. Happened to me also.
Happened to me too :) When I got mine it had a cut wire, but right at the pickup shell for some unknown reason. It was held together by insulation only, making it intermittent. I whittled back a little bit of the shell and soldered the two wires back together. It lasted for years but eventually developed an open coil for some reason.
 
  • secondly i measured the resistance between the primary leads and ground. Here i found something weird: I would measure around 7 ohms between the red (hot) wire to the coil and ground. and around 10 ohm between the orange (signal) and the ground.....
That's probably easy to explain. The TCI red side has 7 ohms to ground and the 10 on the other side is that 7 plus the 3 of the coil itself. Measure the red disconnected to test the theory. With both disconnected should be completely open to ground. My biggest share of problems was with the coil until I put on a used Honda MP-08 that I'm always yappin about on here. Also had a swollen and stuck float needle for awhile that imitated an ignition problem. Be aware that a coil can measure fine but be bad, because the meter is using low voltage to test and high voltage behaves differently.
 
I measured the red to ground with the connector disconnected (see picture above). Tonight after the bike had cooled down I tried to start it. Wouldn't start.

I then measured from the red primary winding at the coil to ground (with the entire wireloom intact) and it gave me similar values as after the test ride. Around 7 ohm.

Tomorrow I'll check again with the spare spark plug to see if it sparks or not.
 
That's probably easy to explain. The TCI red side has 7 ohms to ground and the 10 on the other side is that 7 plus the 3 of the coil itself. Measure the red disconnected to test the theory. With both disconnected should be completely open to ground. My biggest share of problems was with the coil until I put on a used Honda MP-08 that I'm always yappin about on here. Also had a swollen and stuck float needle for awhile that imitated an ignition problem. Be aware that a coil can measure fine but be bad, because the meter is using low voltage to test and high voltage behaves differently.
Second and third pic show the TCI disconnected. I'm guessin' he checked the coil with it like that....
 
A tough one, I'm voting with the bad coil internally. I was extremely butt headed about bad coils on a KZ1300, fought it for better part of a summer, did a lot of fix'n and road side sit'n FINALLY put in accel coils, problem gone. Would run fine til the coils heated up.
a dirty switch contact, wire loom issue, corroded connector, bad spark plug boot, cracked high tension lead, are all "possibles"
 
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Interesting theory gary. Yesterday I was talking to a mate about my bike issues. He also mentioned that the more amps flow, the higher the temperature in the coil. Let's just assume I got the return lines sorted (grounds on engine and frame) that leaves the power feed to the coil. We know that with the ignition on bike not running I get 12.15 volts at the coil. So that's power from the battery. Ain't that to low? The amps go up if the voltage is lower right...?

Would it be interesting to see how much voltage is going to the coil with the bike running, so power from the alternator? I did measure the output during the test ride but on the battery. See post above. I could get a meter installed to see what happens. And could /should I measure the amps too?

While we are on the subject, is the 12.7v and 12.4v with ignition off/on not on the low side? Could this have something to do woth it?
 
That's probably easy to explain. The TCI red side has 7 ohms to ground and the 10 on the other side is that 7 plus the 3 of the coil itself. Measure the red disconnected to test the theory. With both disconnected should be completely open to ground. My biggest share of problems was with the coil until I put on a used Honda MP-08 that I'm always yappin about on here. Also had a swollen and stuck float needle for awhile that imitated an ignition problem. Be aware that a coil can measure fine but be bad, because the meter is using low voltage to test and high voltage behaves differently.

Just a update about this: I just unplugged the orange and red wire to the coil, now there is no circuit between red-ground and Orange-Ground.
 
12.15 volts at the coil is good. Many old bikes don't even see 12 there because of all the (sometimes dirty) connections between the battery and coil. 12.7v key off, 12.4v key on is also about right. You won't see higher until the bike is running and charging.
 
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