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Thread: shitty 4k carburetor tuning

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    Member yakusikimo's Avatar
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    Default shitty 4k carburetor tuning


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    I work as a pizza delivery driver so i stop and start my car alot. When ever i turn off my ke70 and go in the store for 3 min then come back out to start it when its hot, it takes ages to start. most times its like it floods straight away i keep turning it over then slowly apply accelerator till it fires up. It hardly ever fires first turn over if its been longer than 1min. My car always runs better when the choke is halfway out, if the chokes in the acceleration flat spots and theres less power. So i think it runs a bit rich the exhaust always pops when deaccelerate but performance is really "dicky" for engine temp vs air temp

    So the question is: Is this what most shitty 4ks do and will leaning the fuel mixture make it better, whats youre experience with 4k carburetors?

    Where abouts is the fuel mixture screw and does anyone have a 4k carburetor diagram?

    also one of vacuum pipes has been blocked its probly not needed but is there like a hot start thingo

    any help appreciated thanks

    inb4 get a 4age
    if u cant find it grind it

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    Veteran Jonny Rochester's Avatar
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    The carby and vac hoses together compose about 10 different systems, any of which could be your problem.

    If you have no knowledge of all the different systems, you can buy a can of 'stuff' to spray in every dirrection and it may work. Try carby cleaner as a start, then move through your Dads collection, but stop short of painting it red.

    Replace any vac hose that is cracked. Block off any vac hose that goes no where.

    Replace the points.

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    Veteran Jonny Rochester's Avatar
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    If you always need the choke, maybe a air leak somewhere. If not a cracked hose, its the manifold gaskets.

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    Senior Member greeneyes's Avatar
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    Is this what most shitty 4ks do
    nope- I blocked all the vac hoses except the one running the vac advance on the dizzy, took out the 'slow-deceleration' screw on the diaphram and cranked on a few degrees of advance.

    Float level might be too high if its flooding, what L/100km do you get?

    I'll take a photo of the idle screw & mixture tomorrow..

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    Member yakusikimo's Avatar
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    ahhh yes there is a leak on intake underneath the carburetor that i should fix thanks, i didnt know that it would make the choke needed.
    Ive sprayed wd40 through it and the pionts, leads where replaced not long ago.
    If i fix that leak it will probly run alot better.
    cheers jonny you're a great asset to this forum
    Last edited by yakusikimo; 21st May 2009 at 12:33 AM.
    if u cant find it grind it

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    Yes, if you know of a air leak in the manifold, that is the MAIN problem.

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    yeh the fuel consumption is pretty bad but this could also be due to the air leak on the intake i forgot about.
    one other problem i have is when i come to a stop the revs drop all the way down and either bounce of 200rpm or it stops running
    if u cant find it grind it

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    Senior Member greeneyes's Avatar
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    i come to a stop the revs drop all the way down
    That's the air leak leaning it right out.... not enough fuel being sucked in through the idle jet to run it.

    Sounds like it needs a general workover in the carb area. Ours runs around 6.7L/100km on a trip, up around 8L/100km around town.

    We had an auto so our vac system was slightly simpler, but I disconnected everything except the charcoal canister & the vacuum advance on the distributor. I've tried to copy it onto the manual diagram here.

    Last edited by greeneyes; 21st May 2009 at 11:02 AM.

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    where are u located?

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    Quote Originally Posted by yakusikimo View Post
    ahhh yes there is a leak on intake underneath the carburetor that i should fix thanks,
    hahaha c'mon man........

    carbies work on one thing, vacuum! and if you screw with it (ie leaks) it willl have no idea what is going on.

    my theory is your leak is causing you to have less vacume at the carby, and thus it wont be pulling enough fuel through. the choke increases vacume (by choking the inlet) and thus lets more fuel in, allowing you to drive.

    suggestions:

    -fix that damn leak, replace the whole gasket
    -make sure no pipes are leaking, you dont really need ANY of those pipes, just the ones outlined in green above. just make sure they are all interconnected or blocked off so there is no leaks.
    -then buy some carby cleaner and go nuts, reving the guts out of it while spraying it down the top.
    -change points, clean spark plugs with a wire brush

    if worse comes to worse, go and buy a 3k carby. same thing, no pipes. cept for the ones you need. though im told its a good idea to put your jets from the 4k carby into the 3k one. i drove around witha standard 3k carby on my 4k for years, no problems.

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