trivia question ktm lc4

Discussion in 'Thumpers' started by beek-02, Oct 31, 2012.

  1. beek-02

    beek-02 blazing a trail

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    I've owned a few of these now. I've had a 95 Rxc non e-start, 97 rxc e-start, and 00 lc4. The dilema I've ran both the 95 and 00 without a battery no problem. The 97 will not run without the battery connected. While running if you disconnect the battery it will die. It does not have a capacitor nor do I see one in any parts breakdown for the year. Is this something that ktm missed in the mid years? Any thoughts or suggestions?
    #1
  2. bmwktmbill

    bmwktmbill Traveler

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    Beek,
    I don't know the answer to your question, nor do I remember reading an explaination of what the capacitor does and why.

    There are some old threads somewhere for kick starting the machines with capacitors using a home made battery pack to 'maybe' charge the capacitor???

    I have never been clear if you can start a dead battery-dead capacitor bike.

    PersonallyI think you can but you have to kick it enough to charge the capacitor, then it will fire the plug.

    That may be 'just my imagination running away with me'

    Well anyway here's a bump for your question



    bill
    #2
  3. bisbonian

    bisbonian Long timer

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    What is your charging voltage?

    On the vehicles I'm used to, if the charging system isn't putting out enough voltage the engine will die.

    Perhaps this is different, but it's a place to start.
    #3
  4. beek-02

    beek-02 blazing a trail

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    The ktm ignition system uses a permanent magnet generator not an exciter generator. I would not think it would require a capacitor or battery to run.
    #4
  5. AdventureDave

    AdventureDave MMMMM Bundy!

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    OK - another non-answer to your question, but an observation. When I bought my 625SXC (2006) the previous owner had replaced the air fliter/battery box with the old style (pre elec start) airbox (air filter about 3 times the size) BUT as well as unwiring the starter he had to place a tiny (pack of cards size) battery in the new airbox - otherwise it wouldnt start or run. Sorry didnt ask why and I have since rewired the sterter with a lithium battery.

    Cheers

    David
    #5
  6. bmwktmbill

    bmwktmbill Traveler

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    Bump for the mystery.

    Gunner?
    Luke?


    b
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  7. Luke

    Luke GPoET&P

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    I'm not really following the question. :ear
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  8. bmwktmbill

    bmwktmbill Traveler

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    Luke, maybe it's several questions for each of us.

    For me it's as follows.

    The factory workshop manual provides no explaination of how the ignition system works so I do not understand it.

    My '02 has the capacitor.
    I don't understand what it does or how the ignition system actually works on my Adventure.

    Would you be willing to post a few lines on how the ignition system works and what the capacitor does in the system...and ...answer once and for all for me if my '02 Adventure will start with a completely discharged battery and a discharged capacitor.

    In other words does kicking over the engine make the electrical power to fire the ignition and further do the lights need to be disconnected for the machine to start with a discharged battery and capacitor.

    If these are dumb questions please understand it is just my ignorance of how the system works and my fears that some day it will fail.

    bill
    #8
  9. Luke

    Luke GPoET&P

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    Ok.


    The regulator/rectifier requires some sort of energy storage device in order to properly convert the AC power from the stator to DC power. The ignition system requires good* DC power to operate.

    *'good' appears to mean power that never drops below about 5V. It definitely won't operate if the power stays below that 5V point for more than a second.

    The battery and capacitor are both energy storage devices, the regulator/rectifier will work properly with either of them, using both is redundant.

    The capacitor charges pretty much instantly to whatever voltage the stator is able to deliver. If there's a load on it it discharges pretty much instantly when the stator stops providing power.

    There's no good answer to what happens when the battery is discharged or failed because they fail in different ways. Not surprisingly, good quality batteries cause less trouble when discharged than bad ones. Best case, a discharged battery will sit there and do nothing. Worst case, it will short out and the bike won't start until it's disconnected.

    The generator is a permanent magnet type, so it produces power whenever the motor is rotating no matter what is causing the rotation. Faster rotation produces more power, of course.

    The headlight issue is due to the fact that when kick starting, the headlight and ignition are both drawing power from the stator. If there's no power delivered by the battery at all then often the stator can't deliver the 5V that the ignition needs to fire. Turning off the headlight lets the voltage get higher. If there's enough energy in the battery to get even a dim light from the headlight then the stator can get the voltage high enough to fire the ignition.

    So in short: if the bike won't start, turn off the headlight and try again.
    If it still won't start, disconnect the battery and keep trying.
    If that doesn't work, check the kill switch and petcock again.
    #9
  10. bmwktmbill

    bmwktmbill Traveler

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    Luke,
    That was a great post and I understand everything.
    Thanks for taking the time to explain.

    I think your post should be pinned.

    So you are saying my motorcycle will start and run without a connected battery.
    That's valuable to know.

    Is it safe for the elctrical system to run the motorcycle that way until a repacement battery can be found?

    Will the lights operate normally when the are switched on once the engine is running?

    bill
    #10
  11. beek-02

    beek-02 blazing a trail

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    I made it out to the garage today to find out, well I had to assume, exactly what Luke had said. My question was mostly if it is a pmg then why does it require a battery or cap to run? My assumption the voltage regulator (or cdi) does not work unless there is a good 12v power source (Luke confirmed it to be approx. 5V). Seems odd to me that ktm had designed it that way as there dirt bikes use almost the same system but does not require a good power source, cap or battery, to run. I would say it has something to do with the wattage but I believe the rfs pmg is putting out almost the same and I know the trail tech aftermarket kits are in the 120-130watt straight dc range. I wonder if an aftermarket reg/rect possibly from trail tech would remove the need for the batt/cap for the LC4. I guess either way the mystery is solved.

    Thanks Luke and Bill for be persistent.
    #11