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  1. #1
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    Default mikuni vm34 dual carb setup swap cb750

    Anyone have the specs for vm34 dual carb setup for a dual cam cb750?

    My experience with mikuni carbs is limited to snowmobiles, however, i drag raced them for a couple years so I can put one together in my sleep. Anyone who knows the carbs, knows there is an infinite amount of combinations. Also knows that a vm34 carb is universal (snowmobile/atv/motorcycle). However, to apply to a CB750, you need to know:

    Main Jet
    Pilot Jet
    Needle Jet
    Jet Needle
    Throttle Valve
    Air Jet
    Needle Valve

    Knowing the above information, you can put together a set of carbs fairly cheap... Not knowing the above info of a known setup that works (or is close) is a huge undertaking...

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    I'll go out and see what I'm running and where everything is sitting tomorrow and get back to you. I've got a sohc, so I don't know how that might (if at all) affect the performance of your dohc. Other than running a little lean on 1 and 4, my settings were great. How the wishbone intake is set up has a whole lot to do with performance.

  3. #3
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    Any luck?

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    Quote Originally Posted by joeroberts37 View Post
    Anyone have the specs for vm34 dual carb setup for a dual cam cb750?

    My experience with mikuni carbs is limited to snowmobiles, however, i drag raced them for a couple years so I can put one together in my sleep. Anyone who knows the carbs, knows there is an infinite amount of combinations. Also knows that a vm34 carb is universal (snowmobile/atv/motorcycle). However, to apply to a CB750, you need to know:

    Main Jet
    Pilot Jet
    Needle Jet
    Jet Needle
    Throttle Valve
    Air Jet
    Needle Valve

    Knowing the above information, you can put together a set of carbs fairly cheap... Not knowing the above info of a known setup that works (or is close) is a huge undertaking...
    That's why they're so godamm expensive! That and the intakes. They also do not fit in a stock frame. I chopped my frame and barely have room to run them comfortably. good luck, you wont be saving a ton of money like you think unless you already have the vm34's. Check cyclex, they sale the kit.

    PS - MFB, as far as running lean- have you tried to move the carbs in the boots. I open up the slide and aim the throat of the carb into the split of the intake. then tighten down the hose clamp.

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    Gah! Sorry friend, I've been preoccupied with a little friend in town. I wrote everything down, but cant find the damn paper. I'll hop on that in the AM.

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    My needle is shimmed at the second slot from the bottom and main jetted at either 24.0, 240, or 2.40.(the jet was scored up from the previous owner using pliers to torque it down is my guess.)

    Make sure that the boots are cut so that the wishbone intake seats as close as possible the engine and the same for the carbs to the intake. Making a carb stay so that the assembly doesn't sag helps too.

  7. #7
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    And don't hesitate to call Ken at Cyclex with questions. He's got an answer for most any question involving his products.

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    Thanks Brandon. I was hoping for the carb specs of the internal guts of the carbs. Your description of the main would be a "240" which is only one very small piece of the puzzle. For example, a polaris Ultra snowmobile has a mikuni 38mm roundslide carb with ~410main jets. I can provide full specs of this carb from racing, etc. The other pieces of the puzzle that would be needed:

    Main Jet = 240
    Pilot Jet
    Needle Jet
    Jet Needle
    Throttle Valve
    Air Jet
    Needle Valve


    Some may view this information on the cycleX kit, as proprietary information, others dont. Guess I might have to bite the bullet and buy the kit. Then I would have the information that I need for the future...

    Once again, thanks for looking.

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