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Failing NOT CDI it's a TCI , unit symptoms?

Discussion in 'The Garage' started by XS1961, Sep 8, 2012.

  1. XS1961

    XS1961 XS addict!

    Wondered what the symptoms of a failing cdi unit were..Ive only had a couple of TCI models in the distant past, never had any problems with them but recently I fitted a spare complete stock TCI system to mine. Its covered about 600 miles trouble-free but now I have a problem ,its never actually killed the motor but started to intermittently sputter/cut on load around 3-4000, like flicking the kill-switch on/off (extremely quickly)but not all the time. Get her cruising 4000+ & alls fine
    Its NOT the kill-switch, Ive checked. Its not fuel/carbs (Ive swapped em to check, three sets) or rubbers.
    She starts first kick, hot or cold
    Although its both cylinders its not the coil, Ive tried a new one.
    Could vibration damage to a diode cause this?
  2. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    There is the problem of the weak pick-up magnet that's mounted on the alternator rotor. You can test this by unplugging the regulator (removes rotor magnetic field). If the engine runs normally, then the pick-up magnet was weak. The fix is to glue on a new magnet.

    Then again, those TCI circuit boards are old and components could be failing. Some have had success by re-soldering all of the solder connections on the PC board. Several threads on here about the TCI repairs.............try Search.
  3. XS1961

    XS1961 XS addict!

    Thanks RG, Ive just unplugged the reg/rec & run it 5 miles without a hiccup..Trouble is when I re-connected it ,its just run over 5 miles home without a problem..Sods law,Ill have to try that again tomorrow...
  4. retiredgentleman

    retiredgentleman XS650 Guru Top Contributor

    Could just be a loose connection somewhere such as Ignition switch, fuse holder, etc. Another test would be to run a jumper wire from the battery to the ignition coil, thereby by-passing main fuse,ignition switch, kill switch, ignition fuse (if you have one).
  5. xjwmx

    xjwmx XS650 Guru Top Contributor

    One failure is the engine just stops for no reason and with no symptoms, just like you hit the kill switch. But it will start back up immediately if you pull the clutch and hit the starter. This is the only way of failing that I know of that has been definitely traced to the TCI box itself, and it has turned up several times. But it isn't common.

    When mine was doing it I looked at all the solder pads and found a few that had bad joints. You have to look very carefully, and with a magnifier at my age. The bad joint will have a faint ring around the component lead on the solder side of the board. I re-soldered those and fixed it. I then re-soldered every joint in case others were on the way to going bad. No problems with it now in a long time. Re-soldering every joint isn't as dramatic as it sounds. Takes about maybe 15 min. But you need to know how to solder circuit boards.
  6. dwyatt

    dwyatt XS650 Addict

    I was having a problem where mine would seem to drop a cylinder after it got hot in a couple of miles, then be OK once it sat and cooled, but would repeat the problem. I assumed the TCI was doing it's typical thing and replaced it with a new CDI unit but haven't been able to run it to verify that was the problem. Does this sound right to you huys?
  7. XS1961

    XS1961 XS addict!

    I dont, just an ON/OFF toggle-switch , this is a £2.50 item, so worth a try at replacing/bypassing .
    Has absolutely never happened, so good news here, Im hoping !

    Ill try replacing/bypassing the toggle-switch tomorrow & replacing the old/dodgy looking NGK plug caps..
    Fingers crossed

  8. Bushyeyed1

    Bushyeyed1 XS650 Addict XS650.com Supporter

    Mine seems to be experiencing similar issues dying after its warmed up and in about 3-4000 rpm range. @XS1961 did you ever figure out the issue?
    Jim likes this.
  9. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

  10. jussumguy

    jussumguy XS650 Addict

    Does your bike have a kick stand switch? Sometimes that will give you an intermittent problem. You can delete it and connect the two wires together
  11. Bushyeyed1

    Bushyeyed1 XS650 Addict XS650.com Supporter

    No kickstand switch installed on my 1980 G model.
  12. XSLeo

    XSLeo XS650 Guru Top Contributor

    How's your charging system? TCI's don't like low voltage.
    On my 81, Before I got the charging system working as it should. Use a charger to fully charge the battery, the voltage would slowly drop and when low enough the bike started acting as you describe.
    Won't hurt to check.
    Jim likes this.
  13. Bushyeyed1

    Bushyeyed1 XS650 Addict XS650.com Supporter

    Thanks Leo and no offense but, I believe we beat that dead horse in my build thread recently. I am in the market for a stator since it is bad and I already ordered a new rotor since it was on the edge of being bad.

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