1983 Honda Nighthawk 650 gets no power

Discussion in 'Motorbike Technical Discussion' started by chite5b, May 15, 2005.

  1. chite5b

    chite5b Guest

    Drove the bike yesterday and it did just fine, parked it and came back
    and turned the key to find nothing lighting up or working. Tried the
    starter button and got nothing. It is as if the bike is still turned in

    the OFF position.

    Checked all the fuses they were good, checked and charged the battery,
    I do not know what else to do. This morning I turned the key and the
    console lit up, headlight came on, and everything was how it was
    supposed to be. Turned it off and then back on and it hesitated to
    light up but did. Waited 30 min and tried again and again it decided to

    not respond.

    Checked battery and fuses again and they are all good.

    What could the problem be?!?
    chite5b, May 15, 2005
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  2. chite5b

    fweddybear Guest

    Drove the bike yesterday and it did just fine, parked it and came back
    The problem could be your battery..... just because the lights light up,
    does not necessarily mean the battery is good.... it can be weak.. weak
    enough not to do anything else... i would also check the ground wire to make
    sure it isn't corroded.. in fact, check both cables from the battery
    (wouldn't hurt)... if that doesn't help.. replace the battery.... you make
    no mention as to how old it is....

    Good Luck

    fweddybear, May 15, 2005
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  3. chite5b

    chite5b Guest

    nothing lights up, battery registers good with volt meter. battery is <
    6 months old.
    chite5b, May 15, 2005
  4. chite5b

    fweddybear Guest

    nothing lights up, battery registers good with volt meter. battery is <

    What does it register?? as in how many volts? also have you checked the
    battery cables to make sure they are making proper connection? you sould at
    least have lights when you turn the key....unless when you hit the kill
    switch everything gets cut.... if that is the case, maybe its your kill
    switch malfunctioning...I assume you have checked all the fuses with the ohm
    meter too while they are out of the holder??

    fweddybear, May 15, 2005
  5. chite5b

    chite5b Guest

    battery is good, forget how many volts it had but it was within spec.
    Checked all fuses with ohm meter. All of them were good.
    I checked all cables and connections and they are all good, I filed and
    sanded the ones that "looked" dirty.
    No lights when I turn the key.
    Did not think to check kill switch, going to check ignition switch and
    kill switch with the volt meter tomorrow.
    chite5b, May 15, 2005
  6. chite5b

    fweddybear Guest

    battery is good, forget how many volts it had but it was within spec.
    Ok.. meanwhile, I will check the manual to see if I can find anything as
    to why you have no lights....

    fweddybear, May 15, 2005
  7. chite5b

    PQ Guest

    Checking the battery with a volt meter is only a partial test, battery can
    show sufficient voltage and still be useless.
    Check it with a hygrometer. This may help:
    I wasted almost a week looking for electrical gremlins because I tested a
    battery with a voltmeter and it showed enough for me to think it was ok,
    rechecked later for specfic gravity and found several dead cells.
    PQ, May 15, 2005
  8. Don't forget to measure wind speed with an anemometer, and record the
    barometric pressure readings and send up weather balloons to
    investigate winds in the upper atmosphere. Check your weather satellite
    downlinks for
    recent photographs of weather systems over the oceans. ;-)

    Electrolyte specific gravity can be measured with a turkey
    baster-looking device called a "hydrometer", but electrolyte specific
    gravity and terminal voltage checks don't mean a damned thing when your
    battery gets old and has sulfated plates. The only sure test of a
    battery's capacity is a load test.

    Charge up the battery until the voltage reads as high as it can get,
    compare that apparent state of start with how high the float floats or
    count the rising balls and flick the ball-type hydrometer until all the
    little bubbles detach themselves from the balls, and you will have a
    guesstimate of the state of battery capacity.

    Then hook up a load tester, or a headlight bulb of known wattage across
    the terminals and monitor the terminal voltage throughout the test.

    If you hook a 60-watt headlight across the terminals, it should draw 5
    amps at 12 volts. Check the test periodically, watching for the voltage
    to drop below 12 volts. A fully charged 12 ampere hour battery should
    keep a 60-watt high beam lit brightly for 2.4 hours without dropping
    below 12 volts...
    krusty kritter, May 15, 2005
  9. chite5b

    Ari Rankum Guest

    The lights are routed through the kill switch on that bike.

    RCOS #7
    2005 FJR1300AT
    1992 GL1500 (sold)
    1985 CB700SC
    1984 XL500R (sold)
    1979 SR500E
    1971 CL175
    1969 Schwinn Sting-Ray (totalled)
    Ari Rankum, May 15, 2005
  10. chite5b

    fweddybear Guest

    Ok... it looks like I can't find anything on your bike.... (i have
    limited resources) but it any event... if your battery is in fact good...
    then it sounds like you have a faulty ignition switch, or a faulty kill
    switch (if headlights are wired thru this switch) or a main fuse.. make sure
    yo uhave checked ALL of your fuses... this means take them out of the holder
    and check with a volt meter to make sure there is continuity in them...(roll
    the fuse as you do this to insure no break)... then check the fuse holder
    for continuity.....

    Good Luck..

    fweddybear, May 15, 2005
  11. chite5b

    Ari Rankum Guest

    No, I'm not. On my CB700SC Nighthawk, the lights are routed through
    both (starter and kill).

    RCOS #7
    2005 FJR1300AT
    1992 GL1500 (sold)
    1985 CB700SC
    1984 XL500R (sold)
    1979 SR500E
    1971 CL175
    1969 Schwinn Sting-Ray (totalled)
    Ari Rankum, May 15, 2005
  12. chite5b

    PQ Guest

    Correct, hydrometer.
    Sorry-old fingers.

    PQ, May 16, 2005
  13. chite5b

    chite5b Guest

    alright, i found the problem and it was that there was a short that had
    melted plastic onto the contacts.

    It is in the very front of the bike, I do not know what it is called
    but it distributes the power ones the key is turned in the on position.

    I have disconnected everything except the power into it and the switch
    connection and when I turn the switch it still gets very very hot and

    Any idea on what is causing the short?
    chite5b, May 16, 2005
  14. chite5b

    fweddybear Guest

    replace the part that has the melted plastic and make sure when you replace
    it the wiring is in good shape (not shorting out)

    fweddybear, May 16, 2005
  15. chite5b

    chite5b Guest

    the plastic that melted was the plastic cover and has nothing to do
    with the wiring.

    I am cleaning all the contacts and checking all the wires. I still am
    at a loss as to what part of it is shorting out...

    The weater is awesome... man I wish the bike was working properly....
    chite5b, May 16, 2005
  16. chite5b

    fweddybear Guest

    A great place to start would be the wires coming from your ignition
    switch.......since that is where you can't get any headlights..then move to
    your wiring harness... These shorts can be tough to find...good luck

    fweddybear, May 16, 2005
  17. Your ignition switch contacts make a high resistance connection and
    that is melting the plastic? Been there twice, it wasn't a "short" at

    Most people confronted with electrical problems don't know the
    difference between an "open" and a "short" and a "high resistance
    connection" really confuses them, since the "high resistance" is so

    I will explain:

    In an "open" circuit current doesn't flow through it at all, so the
    wiring and parts can't even get hot from current flow...

    In a "short" circuit, current doesn't go through the load you intended
    it to go through. A common type of load is the headlight. If the
    headlight was "shorted out" inside, it wouldn't light up, but enough
    electricity would flow from the battery, bypassing the light, and back
    to the battery, burning up the wiring, if a fuse didn't blow out

    I used the headlight as an example, because it's the biggest electrical
    load on your bike that runs all the time. Your starter draws more
    current, but not through the ignition switch...

    If your bike really does have a "short" circuit from the switch and
    back to the battery, just disconnect the battery and check the wiring
    carefully with an ohmmeter from the wire that had power to it back to
    ground, but be careful, you can make a real fool of your self with an

    I know that because I spent about two hours tracing an elusive "short"
    on an old T-28 trainer, and it turned out I was reading low resistance
    to ground through the damned starter...

    But, back to ignition switch problems. Why do they melt when they have
    a high resistance connection? Switch contacts should have a *low
    resistance* connection, it should measure 1/10th of an ohm or less. If
    the contacts are worn and dirty, the resistance could get up as high as

    1 ohm...

    1 ohm is a high resistance contact for an ignition switch, because the
    power dissipated (making HEAT) through a bad contact is equal to the
    cuurent SQUARED times the resistance...

    So, if a bad switch contact has to carry 10 amps to support all the
    electrical load and the switch contact's resistance is 1 ohm,
    10 X 10 X 1 = 100 watts. Now, you know you can't put your hand on a 100
    watt light bulb when it's lit. 100 watts of heat inside the ignition
    switch is going to melt that switch really quick...

    I have had to replace two melted ignition switches...
    krusty kritter, May 16, 2005
  18. chite5b

    chite5b Guest

    that helps a lot. thanks.

    Sounds like everything I am looking at.

    The plastic is not melting in the ignition "switch" itself but it is
    the "box" that sends power to everything once the switch is turned
    "ON". The plastic melting is right in the area of the constant power
    going to the switch and the power that comes from the switch once
    turned "ON". Only gets hot when switch is turned to ON.

    I guess a test would be to take a jumper and apply power to the box
    bypassing the ignition switch and see if it still gets hot, or would
    that not tell me anything?

    I will take the connections apart and clean them real well and replace
    any wire that does not check out.
    chite5b, May 16, 2005
  19. I went to www.partsfish.com and found a 1983 CB650SC Nighthawk.
    It shows the ignition switch on the "handlebar top bridge" drawing...

    That damned ignition switch costs $125, but if it turns out you need an
    ignition switch, you can propbably buy an aftermarket switch from an
    online catalog place like www.denniskirk.com of from Chaparral

    I see the fuse box you're talking about on the "steering stem fuse"
    drawing. It has some little plug-in fuses that you can get at any auto
    parts stores. Check into the fuse box and see if the sockets where the
    fuses are supposed to go are all corroded and green, or loose and
    burned black...

    If the fuse sockets are burned, you can clean the black oxidiation out
    of the sockets with some stuff called Tarn-X. That's available in
    drugstores and supermarkets for cleaning silverware. It's a mild acid
    that you can soak electrical contacts in until they are clean. Then you
    can flush the Tarn-X away with distilled water...

    It is possible that the power wire feeding the fuse box is grounding
    out and, if there isn't a fuse between the battery and the fuse box, a
    bare wire touching the steering head might be what's getting hot, so
    none of the fuses blow out because they are downstream of an actual
    short circuit. There are about 4 fuses in that box.

    If the fuse box is all melted and too badly corroded you might want to
    look around some electronics store for an aftermarket fuse box to avoid
    paying the Honda $tealer$hip a lot of money for that plastic box that's
    worth maybe $5.00 at most. They would probably charge you $50.00 for
    it, if they had one...

    You may wind up replacing the fuse box with a few inline fuse holders,
    but get the best ones you can, some of those cheapies are really
    Yes, you could jumper around the fuse box, but be careful not to burn
    out anything else in the wiring. If you could find a heavy duty inline
    fuse holder and put a 25 or 30 amp fuse in it just for a test jumper,
    the fuse would blow out before damaging anything else...
    Try that Tarn-X stuff for burned looking connections. If the
    connections have gotten that hot, the tin plating is probably gone, and
    Tarn-X will clean the contacts down to the bare copper...
    krusty kritter, May 16, 2005
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