GSX-R wont start when it's hot.

Discussion in 'Motorbike Technical Discussion' started by lunatic, Apr 29, 2005.

  1. lunatic

    lunatic Guest

    99 750 starts fine when it's cold and runs fine all the time, but if it
    gets to operating temp. and I stop it, even just to get gas, it will
    not start and sounds like the battery is dead or dying. I can push
    start it though and it runs fine. If I let it cool considerably it will
    start fine. The battery is new, I just had the starter checked out, and
    the reg/rectifier seems to be charging. This is infuriating. I don't
    even want to ride it because I have to push start the thing everywhere
    I go.

    An older post suggested it might be pre-ignition. How can I tell if
    this is the porblem and/or how do I fix it?

    Also, my fan is disconnected. Where do I hook this thing back up?
    lunatic, Apr 29, 2005
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  2. Well, you could look up the idle RPM timing specs and the full advanced
    spec and you'd probably find they were something like 10 degrees and 32
    degrees. Then you could put a timing light on the engine and run it to
    see if the ignition advances---if you can find anything that looks like
    a timing wheel under one of the covers...

    I was looking at the parts diagram on and I don't see
    anything like an four-toothed ignition rotor at all. Maybe the signal
    generator pickup is attached to the crankcase, like on a Yamaha, and
    gets its timing signal from the crankshaft itself? I dunno for sure...
    Well, look at the wire coming from the fan motor and stretch it as far
    as it will go. The plug on the wiring harness can't be very far away,
    can it?

    Your owner's manual should have a wiring diagram in it. Look at the
    color code chart and figure out what color wires should be in the
    connector from the wiring harness. Those wire colors may not be the
    same as the colors of the wires on the fan motor, but the plug will
    only hook up one way...

    Your unplugged fan may be your real problem. Modern water-cooled
    engines don't have very much water in the system. About all they really
    do is
    *stabilize* the engine temperature, keeping it *somewhere* between 180
    and 250 degrees F...

    If the water is getting that hot in your engine, the pre-ignition
    that's dragging your starter down may not be from the spark plug at
    all. The pre-ignition may be from a little bit of red hot glowing
    carbon inside the combustion chamber. Or it might be that the gasoline
    is actually dieseling, igniting from the heat because the cylinder head
    is getting so hot. Some early model Kawasaki Ninjas were said to
    actually reach 275 degrees F water temperature...

    I had a Yamaha 250cc 2-stroke diesel on me once. Shutting off the
    ignition didn't stop the motor, shutting off the fuel didn't stop it,
    it didn't quit until the float bowls ran out of gas...

    When you shut your Suzuki engine off when it's hot, does it try to keep
    running for a turn or two, or is it a fuel injected model? One thing
    about FI models is that the ECU shuts off all the gas when you turn the
    key off, unlike carbureted gasoline engines that keep on sucking
    gasoline from the float bowl and keep right on dieseling when they are
    krusty kritter, Apr 29, 2005
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  3. lunatic

    lunatic Guest

    Would the timing/ignition advancing make it sound like the battery was

    And the fan doesn't have a plug on it. It looks like the wires were cut
    for some reason. The two coming off of the fan are only 2 or 3 inches
    lunatic, Apr 30, 2005
  4. Yes, it would make the starter have to struggle. But so would
    preignition caused by overheating. If I was you, I'd work on getting
    that fan running...
    So, check around underneath the fairing in that area, on top of the
    radiator, and around the thermoswitch that's probably in the side of
    the radiator until you find the wires harness that's supposed to go to
    the fan. Your engine really needs that fan to keep the water
    temperature around 200 degrees...
    krusty kritter, Apr 30, 2005
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