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Thread: need help: how to properly set air/feul screw on card?

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    Question need help: how to properly set air/feul screw on carb?

    salam
    dear fellows how to adjust the air/feul mixture on 70cc bikes carb ? what are the default settings i played with them but cant seem to set the mixture ,, my sparkplug gap is set to .63mm which is within prescribed range of .6 to .7 mm..but its tip is quite black,,carbon sooth is accumulated there..
    here is a pic of my carb,, its keihin pc-09f cwc-30 or cwg-30
    [IMG]need help: how to properly set air/feul screw on card? - IMG410[/IMG]
    a video or pic to illustrate it will be very helpful..
    thanks


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    babababababbabuuuuuuuuuuuuuummmmmmmmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm mmmmmmmmmmmmmmmpppppppp

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    ok guys i have tried to set it ,,but mixture settings is not 100% ok,, i first fully closed the air/feul screw in then screwed out one and a half rotation,, that is fist ,, that is rotated three times out from fully closed at 180 degrees rotation each,, ,, if any one knows exact settings plz do mention,,

    now i have another important question,, as u know that the fuel air mixture settings are set by carb and at different altitude the settings are not same,, i adjusted my carb [from mechanic] and went to murree ,, now islamabad is at 500 meters sea level and murree is at 2000 meter sea level,on the way to murree i checked the spark plug at different places and every time i found the mixture to be very very rich ,, that is the carb was extremely black and oily, i tried to play with the screws but i couldnt adjust the mixture to correct proportions and bike had lost all power even in first gearon relatively short flat slope it was stalling even in first gear,, whareas at the sea level of 600 at margalahills it went rocket even at extreme slopes,,
    so after coming home i found that the main jet has to be chnged according to altitude.. to achieve a perfect ratio... so my questions are
    1: to to identify which number of jet to replace for optimal performance..
    2: since to replace to the main jet on current carbs one needs to open the entire carburetor and its very lengthy process .. whareas i have heard that snowmobile have a type of carburetor where the main jet is accessible externally so u can just change it externally without having to open the carb .. just like taking out idle speed screw or air feul mixture screw out... and replacing it.. so are such carbs available in pakistan particularly in islamabad rawalpindi and where at what price.? as an example of such carb here is one
    http://www.teamcalamari.com/pix/20mm/13b.jpg
    20MM Carb Basics
    3: more info can be obtained by searching rejeting carb for sea level.. i have honda ct70 manual there they have shown some plots on how to choose the number of jet .. and those plots are available online as well here i am pasting a link to an excellant site
    Motorcycle Carburetor Theory 101

    thanks..

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    yesterday i cleaned the carb and tried to adjust its carb,,,results are good,,pick is better though not excellant probably the carb air/fuel screw is not adjusted properly..here are the vides of the bike first shows me adjusting the screw second video shows the bike and its sound,,it was raining as well,,,
    i opened the air fuel screw one and a half rotations out from fully closed ,,that makes it 360 degree plus 180 degree,

    YouTube - dhoom yd 70 carburetor air screw adjustement 78cc 4stroke bike keihin chinese replica carburetor.mp4


    YouTube - motorcycle sound after adjusting the air fuel screw on dhoom yd 70


    listen to the sound and comment and rate it ,, any tips welcomed

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    dears during the reassembly one thing confused me ,, that is how to allign the small thing shown in pic which orientation is ok,,,?first or second
    i m talking of the thingy shown above the golden color jet/?,,, it hangs onto the float ball assembly,, for the sake f question i removed the float balls ..
    need help: how to properly set air/feul screw on card? - 10042008869

    need help: how to properly set air/feul screw on card? - 10042008876

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    @asjdsm
    Good research work going on. (Y)
    I dont know how they do it in factory but I used to put it as in 1st pic
    Exploring Machines is my Passion...

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    i installed it like the second ,, i strongly suspect that before opening it this was the config,which was tuned by a mechanic

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    Please help me
    I just opened the carburetor for cleaning but unfortunately this float a little rod and some rocket type of thing came out
    please guide me how should I assemble it back to its position
    Attached Images Attached Images  

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    wait i am writing..

    the one big component is the float balls ..
    the rocket type of thing is float valve ( its a valve ) ..
    the rod is actually a pin which hoilds the float baLL In its place in carb ..


    now to reassemble it ..

    take the rocket and let it hang in the place shown in followiong pic ...

    then place this rocket and float in its place .. and allign it with the corresponding holes in carb ..

    then insert the pin to hold all in its place .. \


    for more details read the following post
    http://china-moto.com/cm/china-moto-...d-description/

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    waiting asjdsm

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    Thanx Alot JAZAKALLAH

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    But still I am confused in setting the pin. please elaborate it if u can

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    Can u edit the pic i've uploaded and mention the position of pin by an arrow?

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    wait i have spare 125 carb lying around .. let me snap few pics ..

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    I just got it
    Thanx alot once again
    So nice of U asjdsm

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    have u changed the position of two screws on the outside of the carb ? one is on the side which has spring and the other is under the carb .. ?
    the one under the carb is for fuel .. adjust it correctly from mechanic .. it needs to be opened a certain amount from fully closed..
    normally its between 1 1/2 turns to 2 turns .. (remember 1 turn means 360 degress rotation .. i.e. when the line is aligned twice )

    the one on the side with spring is for idle speed adjustment .. u can set it just slightly above the point where the bike idels ..

    oh if ur rpm meter is ok .. then just set it so that ur bike rpm meter reads 1200-1500 ..

    also

    the slide tube needs to be inserted in one direction .. read the above refrenced post again ..
    if u do it the wrong direction .. then jaisa hi start karo *** bike .. tho bike bhot shor machaya gi jaisa takreeban adhi race di ho ..

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