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Project Suzuki GF250f

Discussion in 'Your 250cc Projects' started by Callam, May 5, 2020.

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  1. Callam

    Callam Member

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    My Bike:
    Gf250f suzuki
    Done both fork seals, fitted the new air pilot screws and it still won't run properly. It's struggles to start,only starts hand covering the carb. Doesn't idle Then will only run revving past 4k for about 10 seconds then completely dies
    It's now had
    New keyster viton needles
    New ebc 30 pilot jets, (factory)
    Has 90 main jets with correct suzuki washers underneath now
    All little holes and tubes cleaned with no debris
    Orings hve been replaced with fresh viton rings
    New piping
    New denso plugs
    DSC_3470.JPG inlet rubbers good and seal no leaks
    All four plugs are a slight chocolatey colour which usually means its burning OK? But if its all burning OK why does it not want to run?
    Air screws have been 1, 1 1/2 and 2 turns out
    Float heights are set to 20mm like in manual, if I go much more the carb floods. All four cylinders are firing and all four exhaust very similar in temperature .(touch) Had somebody tell me it won't run without the air box. Have made an adapter to fit a pod filter, but that's made no difference, never knew a Carb that won't run on it bare self before

    Any thoughts?
    I seem to keep going round in circles now and nothings changing how it will start and run
    Heeeeellllllpp
     
    Callam, May 28, 2020
    #21
  2. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    CV carbs definitely do require the standard air box and filter, without holes drilled in them or bits removed, to run perfectly.

    I had an fzx250 zeal that ran at 18:1 with just the airbox lid removed - dangerously lean.
     
    • Like Like x 1
    Linkin, May 29, 2020
    #22
  3. Callam

    Callam Member

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    I do not have the airbox, and don't have the rubber boots that fit, there are none in this country for sale
    So it's getting too much air without stock airbox then? Even with the adapter/ restrictors I've fitted with the cone filters it's a 28mm hole with 28mm filter on to do both each side. that sucks, that will mean this bike probably won't ever run now guy who sold me the bike has completely screwed me over
     
    Callam, May 29, 2020
    #23
  4. Linkin

    Linkin The Mechanic Premium Member Contributing Member Dirty Wheel Club

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    Pods straight onto the carbs will not work well. I have seen people use rubber adapters, construct a sort of airbox out of PVC tubing, and fit pod filters on the end. It's a cheap DIY alternative to an airbox.
     
    Linkin, May 29, 2020
    #24
  5. Callam

    Callam Member

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    But if it would be running lean, they why are the plugs on the slightly rich side? I'd expect the plugs to white, but the plugs are dark brown slightly black
     
    Callam, May 29, 2020
    #25
  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    First, before you go any further or ask anymore questions, how much compression does it have?
    If you cannot answer that question then you don't need to answer any more.

    Yes, most bikes will start and run without the airbox. It sounds like you have a fuel blockage if it only runs for a few seconds but I have no personal experience with twin choke CV carbs.
    Are you trying to run it from a remote fuel supply or the fuel tank?
    Have you removed the tap and cleaned it?
    Does the tank have rust or sediment in it?
    Does the fuel tap flow continuously?
    Are the choke circuits clean and functional?
    Are the diaphragms in good condition with no holes?
    We cannot tell what the problem is that you are having because it is probably a combination of things that include not having an air box and we don't have enough information.
    Seriously? These bikes are what as known as 'grey imports' they were not officially imported by the distributor. We all cannot buy parts for our grey imports. They have to be imported from Japan and if they are not available new then you find them on the Japanese auction sites.
    https://www.jauce.com/auction/m265560356
    https://www.jauce.com/auction/d411795694
    https://www.jauce.com/auction/g173567115
    https://www.jauce.com/auction/l587988940
    and so on. If you want to tune your carbs to run without the airbox and air cleaner then fit non-CV carbs and it can be done. If you want to run the existing carbs without an airbox then you are on your own. There is no easy way and there is no one size fits all just 'change this jet and do this' solution. Here is an article about the effort needed to complete the task https://litetek.co/docs/InSearchOfFreeLunch.pdf.
    You will find people that say 'I did it and my bike runs great'. When they present a dyno chart of before and after then I will believe them. Until then it is just talk and talk is cheap.
    And yes, I am trying to help.
    Cheers
    Blair
     
    • Agree Agree x 2
    Last edited: May 30, 2020
    maelstrom, May 29, 2020
    #26
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