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jetting FCR 39

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    jetting FCR 39

    I'm trying to get an old pair of FCR 39 up and running on my Hawk. Currently the engine starts fine but the midrange doesn't work at all.
    I have the following jetting installed :
    - Needle : 0CELV second clip from the top
    - Main Air jet: 200
    - Main jet: 145
    - Slow jet: 52
    - Float level: 9 mm

    Synchronising was not a problem at all.

    Any advice is highly appreciated!
    Cheers, Thomas

    #2
    That needle should be the correct one but usually I run them about 4 clip positions from the top. Everything else looks pretty close.
    J.D. Hord
    Keeper of Engine Nomenclature, 9th Order

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      #3
      FCR 39 jetting

      Originally Posted by Hordpower
      That needle should be the correct one but usually I run them about 4 clip positions from the top. Everything else looks pretty close.
      Hmmm, that would mean that the engine get's even more fuel. I got the impression that the engine got already too much. It runs fine until 3000 rpm, than gets stuck until until almost 5000 (one of the two cylinders does fire correctly- and then with full throttle open it runs ok.) Maybe something is wrong with the carbs ?
      How many tunrns are usually required for the fuel screw and the slow air srew ?
      Which CO value do you usally recomend at between 1000 ~ 1200 rpm ?
      Thanks!!!!!

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        #4
        Hard to say what the problem is. The cables are both attached to the same points on the cable wheels, right? IE, the slides are opening at the same rate? The fuel screws should be ~ 1.5 turns out, the air screws I usually set ~ .5 turns out. You might have to find a good dyno facility to get it sorted.
        J.D. Hord
        Keeper of Engine Nomenclature, 9th Order

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          #5
          Maybe I missed some info (or you Pm'd it) but what is the configuration of your motor? Is it stock or has it had any work done to it? What exhaust are you running? Also where are you located?
          Faster than your mother... She's what the pros use.

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            #6
            FCR jetting

            Originally Posted by Crash
            Maybe I missed some info (or you Pm'd it) but what is the configuration of your motor? Is it stock or has it had any work done to it? What exhaust are you running? Also where are you located?
            The engine is not stock, it's a 780cc and it's an aftermarket exhaust. I know that's probably not what the so called FCR kit was made for. However, the engine is far from running, I had almost fuel draining out of the exhaust between the connection of the end pipe and mid section, which why I thought something with the float level must be wrong. It's currently not about optimising, but get it running at least.
            Unfortunatley, I do live in continental Europe and the support over here is lacking. The Hawk was never a racebike here.
            Thanks for any help !!!!

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