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Thread: DCOE Carb help? - Carb bogging down at acceleration

  1. #1
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    DCOE Carb help? - Carb bogging down at acceleration

    OK - so my Civic 1200 has a single weber 40 DCOE. It idles fine, but when I put my foot down, the engine bogs down and dies if I dont let up. If I very slowly press the accelerator I can get a fairly smooth acceleration with some slight "popping" in the exhaust, but nothing bad - but that is only if I do it VERY slowly.

    All this is while I am in neutral. If I am driving, a similar thing happens, though it is a little worse. If I step on the gas the nose dives and if I dont let up the engine will die too.

    My jets are 125s.

    Any ideas where to start? I have a weber book but it isnt really helping. I didn't post this in the Honda garage because it isnt a honda issue (they didnt come with weber DCOE's!)

  2. #2
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    what size chokes have you got in there? I have my dellorto 40's and had to pull the 34mm chokes in place of the 32mm's chokes as it was bogging too bad

  3. #3
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    Hey there Kurt....

    I have no idea what size chokes. I got it with this engine and I know it used to work with this setup.

    Will it say on the chokes if I pull them?

  4. #4
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    I know nothing about that particular carb, but it sounds like an accelerator pump issue. just my .02

  5. #5
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    Quote Originally Posted by avianman
    Hey there Kurt....

    I have no idea what size chokes. I got it with this engine and I know it used to work with this setup.

    Will it say on the chokes if I pull them?
    If it worked before its likely something else but yes if you pull them out they will be clearly marked

  6. #6
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    Initial thoughts are that the chokes are too big, but also could be because you don't have enough ignition advance. Webers give quite a slug of fuel on tip-in and you need more advance at low rpm to deal with it.

    Do you know what the distributor specs are? If say 8BTDC is stock timing you will find that 15BTDC will make a world of difference. But depending on your stock ignition curve, 15 degrees of base timing might be way too much at the top end, and you might need to get your distributor modified to dial it back at high rpm.

    BTW The choke size is usually cast into it. You can juuust kinda see it at 5 o clock on the one on the left here. After you remove the air hornm they should be able to be wiggled out with your fingers.
    Hidden Content Originally Posted by datsunfreak
    No Kev, you are eating a duck fetus.

  7. #7
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    I advanced the timing as much as I could and it seemed to have quite an affect! I can't tell the actual degree of advance as there arent numerical indicators on my engine. Still bogs a little but not as bad. Im going to keep playing with it and see...

    I might lower the jets as it looks like the plugs are a bit fouled.

  8. #8
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    The way it works is that the idle jets are only in play until about 3000rpm (and by then they are gradually phasing out). So if you are having a stumble at about 3000rpm, then it's more likely an issue with your main jet or emulsion tube, rather than the idle jet.

    Keep en eye on the ignition though, it might not tolerate so much advance at the top end, but also go over your ignition system carefully, renew the plugs, check your points gap, cap and leads. Basically if your ignition system isn't 100% it won't help.
    Hidden Content Originally Posted by datsunfreak
    No Kev, you are eating a duck fetus.

  9. #9
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    BTW, advancing it all the way probably isn't such a great idea, btw

    Pull the jets, emulsion tubes and correctors and verify the size of your idle jets. Also you need to verify the size of the chokes, since the jet sizing is done relative to the size of the choke.
    Hidden Content Originally Posted by datsunfreak
    No Kev, you are eating a duck fetus.

  10. #10
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    I would pull your chokes first and foremost. I can almost promise if they are larger than 32mm they are overkill for the 1200.

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