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Thread: franken keihins

  1. #1
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    franken keihins

    only looking for i've actually done it answers here so don't speculate.twin keihin 40mm carbs put on a 700 with a single pulse line.has anybody run 2 fuel pumps off a single pulse line.i can configure the lines to keep the length short,just don't know the effect on the pulse cylinder or jetting for that cylinder or the pumps themselves.i'd be running the mag carb and one of the remaining 2 from a triple set.the cen carb would have to have the vee feed removed and a brass elbow pressed in to make a single pump setup but i'm not confident that the cast return restriction would keep enough fuel pressure and i'd have to get some really small jets to set the pressure.i figure something like a 45 pilot.


  2. #2
    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    Why not add another pulse fitting on the other cyl?

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    I would think maybe use the mag and center carb and just use a single pump like the stock twin setup. Then just cap off the second fuel inlet on the center carb.

  4. #4
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    A. i don't want to pull the jug and split the cases allthough i added one to the pro when i had the motor out and just pulled the cen jug.B not sure i can get jetted down small enough for the return jet to get enough pressure running just one pump.i certainly don't know what the size of the casting is on a twin set of 38's running one pump.my triple pump set of 42's runs a .060 restriction,i figure something like .040 for a twin pump-twin carb setup,and .020 for a single carb,and then even less for a twin carb-single pump.whats the smallest main jet a 50?? and a pilot?? 32?? 28??

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    She likes the bike. But the ski gets her wet!!!! xlint89's Avatar
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    No need to split the cases. We've installed fittings into the fuji reed spacers with success. Can't see why you can't drill one into that area on the domestic?

    Then you would only need to remove the carbs, intake and reeds. Could prob drill it in place. just shove some clean paper towels into the hole and use grease on the drill bit to catch all the filings.

    just a thought

  6. #6
    Rasta Mon Condoms We Be Jammin!!!!! TxVirageTx's Avatar
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    the question i'm looking for an answer is why not 2 pumps on one pulse line???i get that the added volume would detract from the intake charge push and draw,but HOW much,and any real effect on a 6500 rpm motor??

  7. #7
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    You may see more than 6500 RPM on that motor. I have gotten over 6700 on my 700. But then again that was on the cool waters of Lake Michigan.

  8. #8
    casey67's Avatar
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    The early 700 cases were drilled and tapped for a pulse fitting on both cylinders,I'm not sure when they stopped doing that.Have you taken a good look for a block off plug on the front cyl ?

    I did install 3cyl 40's on a 700,just knocked off the PTO carb. I ran it that way for a couple seasons,but with little use.
    It ran real good with close to factory 1050 jetting,142 mag-140 pto,42 mid and 65 lows.
    At one point I did check fuel pressure and it was good,around 2 psi/idle.

    Maybe make up a tee and test the pulse signal,with a single hose attached to a fuel pressure/vacumm guage - I saw 4 inches vacuum and 4 psi -swings back and forth when cranking.

  9. #9
    SPEED KILLS, BUT YOU GET THERE QUICKER Keddano's Avatar
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    I don't think you would lose much. The little extra line off the T and the diaphragm in the second pump isn't that much volume to draw down.

  10. #10
    ThrottleOut's Avatar
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    I was thinking about doing this on either the 'Cane or the SLH... I think it could be a nice upgrade.

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