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Thread: Jetting A Koso 30mm Carb?

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  1. #1
    Join Date
    Mar 2007
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    707

    Jetting A Koso 30mm Carb?

    ANYONE HAVE ANY EXPERIENCE/SUGGESTIONS FOR SETTING UP A KOSO 30MM CARB?

    I WILL BE INSTALLING A NEW KOSO 30MM CARB THIS WEEKEND. I WILL BE PUTTING THIS ON OUR BIG STROKER MOTOR, A 47 STROKE 53 BORE A/C ALUMINUM CYL. ENGINE WITH BIG PORTS.

    WE HAVE BEEN USING A 28MM KEHIEN, BUT THE SLIDE/THROAT OF THE CARB IS ALL WORN OUT.

    JUST LOOKING FOR BASELINE JETTING SUGGESTIONS, AND WHAT NEEDLE IS BEST. SHOULD I INSTALL THE NEEDLE FROM OUR KEHIEN 28?

    THANKS!

    DAN

  2. #2
    Guest
    I do know the needle is set different on the KOSO than the Keihin.
    The needle should be set at the 2nd notch from the bottom where your Keihin should be 2nd notch from top. But your jetting is up to your builder who should of told you where to go on the jetting. Your elevation and humidity will change from state to state. This is all I can help you with.

  3. #3
    Join Date
    Mar 2007
    Posts
    707
    I am the builder. I have just never run a koso 30mm carb, and was looking for input from anyone who has. i hope I made the right decision with getting this instead of a new keihin 28.

  4. #4
    Guest
    No you didn't its an awsome carb I promise you try to start at a 145 main and a 45 pilot jet would be my way of thinking. Koso is a great carb tho. Hope this helps.

  5. #5
    Join Date
    Mar 2007
    Posts
    707
    Well... This Koso carb. won't fit the intake boot or air filters that i used with the keihin 28mm carb!

    And also the overall size of the carb is much bigger. Even if it did fit my intake boot, it is too close to the cylinder air-shroud to mount up straight.

    Looks like you HAVE to buy the Koso intake or similier with the "bolt on" style boot.

    So not sure what I'm gonna do now...

    The Extra $40.00 for a new keihin is less then the cost of a new intake!

  6. #6
    Guest
    Yes you have to have a 28 to 30mm boot type like the koso. I don't know what kind intake your running but you may be able to buy the fittment for the 30 to fit your intake call Snyders in the morning Shawns a good ol boy he will help ya out.

  7. #7
    Join Date
    Mar 2007
    Posts
    707
    I have the titanium high flow intake with the round rubber boot with two clamps.

    The Koso carb includes a "bolt on" style boot for attaching to the "koso" bolt on style intake manifold. Doesn't work with my intake manifold though.

    I think the new stage 6 intake might work with it as well... but not sure.

  8. #8
    Guest

    Carb

    Thats what we used to run. The same kind till now we run ported intakes. What are you going to do with the used Keihin? PM me and let me know.

  9. #9
    Join Date
    Mar 2007
    Posts
    707
    My intake is ported. And I/m not sure yet, but I'll let you know. i might have a brand new koso 30 for you though. It's still in the box never installed at this point.

  10. #10
    Join Date
    Mar 2007
    Posts
    707
    I'll have to get back to you next week. I bought this carb. from Marc (Hot Quads), and he is at the Nationals racing this weekend. Honestly Marc has never run one of these, so i am treading new ground for him. I want to see what other options he has for me... he was out of the 28mm powerjet stage 6 carbs, otherwise that is what I was going to buy.

    Maybe Gary will reply with ideas as well...

    Dan

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