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Thread: please help carb ivans jet kit

  1. #1
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    please help carb ivans jet kit

    Hi all hope you are all well hoping some one can help me I have fitted K & N pod filters and ivans jet kit set as per instructions a few months ago but cant seam to get the bike to run right above 3000 rev all good but below when you open up it as if there is not enough or to much fuel I have up jetted the pilot jets from 35 to 38 and 2 1/2 turns out still the same so reduced the fuel to 11/2 turns but still the same carbs are all balanced up nice the bike was running really well before but don't know what to do now.
    thanks for any help

    mods so far
    zzr cams
    4+ advancer
    full s/s black widow exhaust
    K&N pods
    ivans jet kit
    ivans air box removal kit
    zrx1200 wheels
    air block off plates
    loads of kendo bits
    I've spent most of my money on alcohol, women and motorcycles............the rest of it I just wasted

  2. #2
    Join Date
    Jul 2017
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    Re: please help carb ivans jet kit

    From reading your post it seems that it's fine below 3000, but runs badly above.

    Just to be clear, carbs work on throttle openings, not revs, so do you mean idle and part throttle is fine, and then when you crank it open (around mid to full) it's bad?

    If so your pilot jets and fueling screw adjustments you're making wont help. If it's running well at idle and part throttle leave the idle jets/screws along and look at the main jets and needle heights.

    Does it run rough as you open up from part to mid-throttle and then smooth out again at WOT? If so your main jets are probably ok and it's just the needle heights.

    Start by moving the needles up a bit to open the jets up for mid throttle. If it doesn't work move to bigger or smaller main jets and see if this helps - you need to find out if it's going rich or lean. I'd maybe try going richer first as it's the 'safer' way to tune.

    I bought an AFR gauge years ago and have it fitted in the exhaust so I can monitor the ratio on the fly. They are a tad pricey (close to 200 quid) but cheaper than taking it for a tune up and can keep them for future tuning/bikes.

  3. #3
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    Re: please help carb ivans jet kit

    Hi No sorry running bad below 3000 but fine above
    I've spent most of my money on alcohol, women and motorcycles............the rest of it I just wasted

  4. #4
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    Re: please help carb ivans jet kit

    So running rough on idle and part throttle.

    Yeah will be idle jets and screws then, but if no changes when you make adjustments you need to make sure the rough running isn't anything else like air leaks etc.

    Do you have a Gunson Colortune? They are pretty good for getting idle set correctly and pretty affordable.

  5. #5
    Join Date
    Jun 2014
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    Re: please help carb ivans jet kit

    Quote Originally Posted by noggin View Post
    So running rough on idle and part throttle.

    Yeah will be idle jets and screws then,

    That's where my money would be (albeit there may be shite in the casting orifices @ the butterfly's) and we all know the answer is
    What Goes Around..........!!!

  6. #6
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    Re: please help carb ivans jet kit

    Ok thanks buddy i will get a colour tune and try that
    I've spent most of my money on alcohol, women and motorcycles............the rest of it I just wasted

  7. #7
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    Re: please help carb ivans jet kit

    Quote Originally Posted by ZRXNige View Post
    That's where my money would be (albeit there may be shite in the casting orifices @ the butterfly's) and we all know the answer is
    But it was running fine before the upgrade must be fuel mix related
    I've spent most of my money on alcohol, women and motorcycles............the rest of it I just wasted

  8. #8
    Join Date
    Jun 2014
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    8,468

    Re: please help carb ivans jet kit

    Lets hope so Mike as its an US clean if it is.

    Im intrigued as to why you have fitted bigger pilots though although Bryan went through this phase and then went back to stock IIRC


    As an aside, have you tried lifting the needles a notch and do wonder if its something as simple as the vacuum stub covers being split / not sealing correctly
    What Goes Around..........!!!

  9. #9
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    Re: please help carb ivans jet kit

    Quote Originally Posted by ZRXNige View Post
    and do wonder if its something as simple as the vacuum stub covers being split / not sealing correctly
    Yeah that was something I was mentioning - make sure everythings sealing first before fiddling with the carbs. I had rough running once and there was a leak on one of the inlet rubbers.

  10. #10
    Join Date
    Jun 2014
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    8,468

    Re: please help carb ivans jet kit

    and is always tricky when troubleshooting from afar
    What Goes Around..........!!!

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