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Thread: How can you check to see if the stator and magneto are bad?

  1. #1
    Join Date
    Dec 2006
    Posts
    55

    How can you check to see if the stator and magneto are bad?

    Is there a easy way to see if the magneto and stator are still good?

  2. #2
    Join Date
    Jan 2007
    Posts
    10
    YFZer, have been reading your posted problems for the last couple of days,and it sounds like your problems are of fuel delivery nature(may have clogged leak jet and such),have you tried disassembling your carb. and spraying everything out with cleaner. Raced with someone over the summer who couldn't get his machine to start with starter and missed the race,freinds from afternoon race helped him locate the problem in the carb,cleaned it out,and raced the afternoon race with no problems..... just a thought for you to ponder before tearing your whole machine apart.

  3. #3
    Join Date
    Mar 2006
    Location
    Mass
    Posts
    74
    If you have the service manual you can look up the components you need to test. They give you resistive values so all you need is a meter that tests resistance. Plug the leads into the connector of what your testing and if the reading is between the #s they give you its good if it doesnt replace it.
    PM me if you need the specs.
    Rich Joseph
    YFZ 450
    #11x
    NEATV MX
    www.spasticdesign.com

  4. #4
    Join Date
    Feb 2004
    Location
    Tunkhannock. PA.
    Posts
    339
    Unique Charging System Characteristics - Yfz450
    The YFZ450 Charging System is designed to
    supply at low to medium engine rpm a maximum
    charging rate with the headlights in the
    ON position. Under some conditions (e.g., low
    speed with cooling fan running frequently or
    continuous high rpm riding), it may be necessary
    to ride with the headlights in the ON position
    continuously to maintain a fully charged
    battery.
    If a customer complains of the battery discharging
    while riding, first check the condition
    of the battery.
    NOTE: If improperly charged or boost charged,
    these compact batteries could overheat and
    become permanently damaged. To prevent
    overheating, charge the battery using a low
    output charger (e.g., Optimate III, ACCOPTIM-
    AT-E3), and test the battery to make
    sure it is in good condition. Next, Check the
    output of the charging system.
    To avoid mis-diagnosis, follow these procedures
    and specifications in the order below:
    1. Minimum key off (battery voltage must be
    12.80 VDC).
    • Voltage too low: recharge and load test
    the battery.
    2. Measure the battery voltage at idle. *It
    should be 14.0 ~ 14.9 VDC before the cooling
    fan starts to cycle ON and OFF.
    • Voltage too low: check the stator coil
    resistance. The correct specifications
    are:
    – Yellow to Ground = 0.22 ~ 0.60 ohms
    – White to Ground = 0.29 ~ 0.84 ohms
    – Out of Spec: replace stator assembly
    • Voltage is too high: check wire continuity
    (particularly the black wire which
    should have continuity between the
    Ground). The Yellow/Red wire should
    have continuity between the lighting
    coil and the regulator.
    NOTE: If continuity checks good, replace the
    regulator assembly. (Commonly, both headlights
    are burned if the regulator has failed.)
    • Voltage Okay:



    NOTE: Do not check the battery voltage at
    5000 rpm as explained in the Service Manual.
    Charging output will decrease as rpm increases.
    This is a normal characteristic of this
    model.
    *Since the system normally discharges anytime
    the cooling fan is ON, all testing must be
    done before the fan starts to cycle on and off.
    Otherwise, the maximum measurable battery
    voltage will be lower than 14.0 VDC.
    SUBJECTS: 1. Unique Charging System Characteristics - YFZ450
    2. Introducing YFZ450 Charging System Resistor Kit -
    Resistor Kit for Competition Usage
    3. YFZ450 Resistor Kit Installation Instructions

    Check the radiator for blockage and
    correct as required.
    Advise the customer to use the key
    switch to turn the engine off. Only
    use the engine switch (on the handle
    bar) in an emergency.
    Advise the customer to switch the
    headlights ON to increase the charging
    output.
    Introducing YFZ450 Charging System Resistor Kit -
    Resistor Kit for Competition Usage
    Symptom:
    As explained in the previous subject (page 1),
    the YFZ450 Charging System is designed to
    supply at low to medium engine rpm a maximum
    charging rate with the headlights
    switched to the ON position. If the headlights
    are removed for competition use, the unit may
    experience battery discharging.
    Remedy:
    Install the YFZ450 Resistor Kit. The kit contains
    a ceramic resistor which takes the place
    of the headlights to maximize the charging
    rate, plus it provides a higher temperature fan
    thermoswitch to minimize current draw. The switch is
    located sitting on the bike the upper right switch
    NOTE: This higher temperature is still low
    enough to not cause engine overheating.
    The kit is optional for competition use and warranty
    does not apply. The kit was developed to
    allow maximum charging and reduce battery
    load.
    2005 D6 PA.State Harescramble Series open C class Champion. and D6 overall Champ

    2006 Open B 3 third place in Pa and in D6

    District 6 XC #34

    06 YFZ 450
    2007 Sponsors
    MSR / DR.D, Duback Racing Development /GT Thunder/ Houser Racing / Hiper technology / /BDATV club/Cardio Stack/Keystone Outdoor

  5. #5
    Join Date
    Oct 2005
    Location
    mi
    Posts
    2
    ok checking stator white is 1.1 ohm and yellow is also 1.1 assuming bad stator. can someone confirm. havent got a manual yet. thanks

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