Hard Starting KZ1000

Discussion in 'Motorbike Technical Discussion' started by messenger1, May 2, 2005.

  1. messenger1

    messenger1 Guest

    Greetings all. I have a 1982 KZ1000 engine, with Wiseco 1105 bigbore and a
    set of GSXR flat slides and 4-2 pipes. This engine is absolutely the most
    cold blooded thing I have known since my sister in law. When trying to start
    it over the weekend, it popped and kicked for about 2 minutes before
    sputtering to life. I didn't run it very long as it sounded like a v-twin
    and was emitting nasty fumes.As I was starting it, I noticed 1 of the head
    pipes (no2) was actually glowing red hot. Pulled the plugs and they looked
    ok albeit a bit sooty. I have a Boysen electronic ignition installed and may
    have misinterpreted the timing advance instructions. What would cause 1 pipe
    to get far far hotter than the rest? carbs? ignition?

    Tom B
    messenger1, May 2, 2005
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  2. Is that a completely different set of carbs from the smoothbores that
    you were talking about before, the ones that didn't seem to be VM29's
    or VM33's?

    Do those "GSXR flat slides" have accelerator pumps? You wouldn't want
    to twist the throttle grip and squirt a bunch of excess gas into the
    cylinders on start up, you'd want to use the "choke" correctly...

    You said that you were going to save all the information I gave you
    last time. It's still available, Google.com has archived everything
    I've said about carbs over the last few years.
    Does your wife know you've been hitting on her sister? Do you think she
    won't find out? ;-)

    Initially, the fuel/air mixture is too lean for starting because your
    carbs are dirty, the idle mixture screws are set wrong, or you just
    don't undertand how to use what passes for a "choke" on Japanese
    carburetors. DO NOT twist the throttle when you push the starter

    If you will google up "kaybearjr@aol +choke" you can read what I've
    explained about chokes on Japanese motorcycles. I've explained it at
    least 100 times. They don't HAVE a choke, a whole different strategy is
    required to start an engine without a choke...
    Lean starting mixture. but at least it started...
    Engine was running on 2 cylinders, and your old alcohol-containing
    gasoline broke down into nasty-smelling aldehydes. Etymology: German
    Aldehyd, from New Latin al. dehyd., abbreviation of alcohol
    dehydrogenatum dehydrogenated alcohol
    Date: circa 1846
    : ACETALDEHYDE; broadly : any of various highly reactive compounds
    typified by acetaldehyde and characterized by the group CHO
    : a colorless volatile water-soluble liquid aldehyde C2H4O used chiefly
    in organic synthesis
    Acetic acid is what makes vinegar smell the way it does. Aldehydes and
    vinegar smell bad and make your nose and eyes water. Don't run your
    engine in the garage and breathe the fumes.
    Rich mixture. Maybe from flooding the engine because you didn't
    understand how the "choke" works, and you twisted the throttle grip, or
    maybe the previous owner of the carbs set the idle mixture screw richer
    on #2 cylinder or maybe the float level is too high, or the float valve
    is stuck...
    misinterpreted the timing advance instructions.

    If you set the timing too far advanced, the starter would have to
    struggle against preignition. If you set the timing retarded, the
    starter would have a much easier job...
    Rich mixture. The ignition would work the same way on all four
    Modern electronic ignition systems are very reliable. They either work
    right or they don't work at all. Motorcycle carburetors are
    misunderstood by riders. This misunderstanding causes most starting
    problems. Clean your carbs, adjust them correctly, use the "choke"
    correctly, and keep your carbs clean and they won't give you a lot of
    problems. And, keep your battery charged up so you won't have
    electrical problems aggravating your misunderstanding of your
    krusty kritter, May 2, 2005
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  3. messenger1

    messenger1 Guest

    same ones, poor description on my part! They are apparently early GSXR
    smoothbores WITH accelerator pumps
    saved and read and re-read countless times thank you ! I have cleaned them
    once and bench synced them as per your reccomendations, not much difference
    though, maybe another cleaning ?
    shes a hottie so its worth the risk :)
    have never used the throttle when starting except when it was popping and
    kicking like it just needed a little push to start.

    I've read and reread all I can find on that topic, but I'm still dumb as a
    brick, what exactly does the "choke" accomplish then?
    ok, carbs need another cleaning I'll assume?
    brand new gas fresh from the station, tank is spotlessly clean and have an
    inline filter attached
    ok will try again without throttle or choke when it gets a bit warmer, just
    to discount my sisinlaw theory
    now and then while trying to start it, it seems to hesitate like theres a
    huge load of compression to overcome, I'll re-read the timing instructions.
    thanks again krusty, I'll pull them off again, try re-cleaning and see what
    happens. Incidentally I have a vacuum operated petcock installed because I
    don't have enough clearance between the tank bottom and top of the engine
    for a Pingel. I had to make a vacuum port out of a drilled screw, installed
    in one of the test ports on the carbs, could robbing this minute bit of
    vacuum from the carbs be part of my probs?

    regards & TIA
    messenger1, May 4, 2005
  4. The idle jets are have really tiny holes in them, the orifices are only
    0.012 to 0.016 imches in diameter, but if you remove them carefully
    with a slot screwdriver that fits the slot perfectly, you can clean the
    orifices out and clean out the cross-drilled emulsion holes too. If you
    follow the procedures I outlined for removing the EPA anti-tamper plugs
    and counting the turns it takes to screw the idle mixture screws all
    the way IN and then remove the screws, you can squirt Berryman's B-12
    Chemtool aerosol carb cleaner through the passages. You can squirt B-12
    into the idle mixture screw holes and it should come out the pilot air
    intake hole in the carburetor bell mouth, it should come out the hole
    the idle jet screws into and it should come out through the three idle
    mixture ports in the carbutetor throat downstream of the throttle
    butterfly. You can squirt B-12 in the hole where the idle jet goes
    while holding your finger over the pilot air intake hole and it should
    come out the three mixture ports and the
    hole where the mixture screws go. If you use up a whole can of B-12
    douching out your carb, it's less than $3, money well spent...
    The "choke" is a seperate tiny carburetor built into side of each main
    carburetor. There is a tiny valve in a *air* passage that bypasses the
    main bore of each carburetor. When you move the "choke" lever to the
    full "ON" position, the tiny valve is opened, and vacuum from the
    engine downstream of the throttle butterfly sucks fuel and air through
    the bypass port. This
    "choke" system also needs the help of fuel air mixture coming from the
    idle jets to work just right...

    If you twist your throttle grip while you're cranking the engine over
    with the starter, there isn't enough vacuum to suck fuel air mixture
    through the bypass hole. If you twist the throttle a few times, you
    will squirt a lot of gas from the accelerator pumps into the carbs and
    flood the engine.
    If the exhaust still stank really bad when you started the engine, it
    was running much too rich, kicking out hydrocarbons and carbon
    monoxide, and some of the fuel molecules broke down into the stinky
    stuff called "aldehydes".

    (Exhaust emissions from rich mixtures and incomplete combustion are
    what led to all the pollution control equipment that modern motorcycles
    are being afflicted with. Honda is a world leader in engine
    development. They wondered if something couldn't be done with the
    broken down molecules of fuel that normally got kicked out the exhaust
    pipe. They built a special 400cc single cylinder two-stroke engine with
    an exhaust throttling valve that trapped exhaust gasses for long enough
    to allow the broken down fuel molecules to *recombine* into a burnable
    mixture. Honda won the Dakar Rally with that "advanced recombinant
    technology" motorbike. It got 40 mpg, compared to the 15 or 20 mpg a
    regular 2-stroke would have gotten.)

    No, you need to apply the so-called "choke", just don't twist the
    throttle grip at all. And, to make the tiny carb in the bypass port
    work right, turn your master idle knob all the way counterclockwise so
    the throttle butterflies are completely closed. The master idle knob
    will be underneath or on top of the carbs.

    With the throttle butterflies completely closed, you will have enough
    vacuum to suck fuel out of the float bowls, through the bypass, and out
    the idle mixture ports. When the engine fires up, you will have to very
    carefully operate the throttle to avoid squirting a bunch of excess
    gasoline into the cold engine and flooding it. You can adjust the
    master idle knob to the right idle speed when the engine warms up.>
    Somebody asked that question to one of the technical columns at one of
    the motorcycle magazines. The answer was that the amount of vacuum
    required to open the petcock was so small it wouldn't affect anything.
    I think the wiriter's original question expressed concerned that the
    vacuum was affecting carb syncronization. Anyway, that vacuum just
    opens the petcock up and then there is no further air flow through that
    line. If you still think the petcock's vacuum requirement affects your
    engine's starting or running, you can always turn the petcock to PRI...
    krusty kritter, May 4, 2005
  5. I'm not an expert here, but I recall reading a post on a web forum about
    someone installing later model carbs on a KZ. He determined that the KZ
    with its more upright cylinder configuration was keeping the carbs from
    being level since they were designed to be used with a more inclined
    cylinder head. He custom built some intake adaptors so the carbs would be
    level. If this is your situation, I hope it helps.

    Otherwise, the popping and banging and red-hot pipe would seem to indicate
    and out-of-time engine.


    - Nate >>
    Nate Bargmann, May 13, 2005
  6. messenger1

    messenger1 Guest

    hmm... I never even thought about carb positioning as I thought since a
    bike is rarely level unless stopped the positioning would not matter? I
    installed this engine in a KZ750 frame and it and the carbs are level to
    the ground when the bike is upright, but I have no idea of the position the
    carbs were in when installed on the original engine they were intended for
    (an early model GSXR.) I've cleaned the carbs twice as per Mr. Krusty's
    directions and advice, but have never been able to decipher the handwritten
    timing instructions that came with the Boysen ignition. I just set the
    timing to where it would run, started it and adjusted it till it ran at what
    "sounds" like a decent timing advance. My timing adjustment consisted of
    starting the bike, getting it warm enough to idle and then rotating the
    adjuster till it would rev smoothly without pinging. I guess I should try
    contacting Boysen for a detailed installation sheet with proper timing
    instructions. I bought this one off eBay and the original instructions were
    not included but the seller had drawn up his own diagram and instructions.

    thanks again all for the invaluable input and advice!

    Tom B
    messenger1, May 14, 2005
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