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Manifold build for carb conversion.


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  • Manifold build for carb conversion.

    I bought a couple of Mikuni VMs to the replace the BS38s on my TX build. These come in a kit form and include manifolds and cables specifically for XS650s. Unfortunately the fit is less than ideal, the cable interferes with the petrol taps so the carbs have to be canted over at quoted an angle. I contacted the seller and he advised that the kits fit most XS650s, but as they are not all the same, don't fit others.
    I explored a couple of ideas: Making a spacer to site the taps further out so the carbs can sit upright, making longer manifolds to place the carbs behind the taps or fitting a sleeve over the carb spigots so they would fit the original manifold boots. I tried the spacer for siting the taps further out, but that was just plain ugly and I passed on the sleeving idea, as the spigots are a rough cast finish so I have to turn them down to fit a sleeve. So, new, longer manifolds.

    To turn the manifolds up from a single piece would require a 90mm round piece of stock, that waste a lot of metal, produce bin loads of swarf and take forever to turn down. So, I made a couple of flanges from 25mm thick aluminium, and turned the spigots down from a 50mm piece of stock, made them an interference fit and pressed them together, then polished them and pressed two brass spigots into the manifolds for syncing.

    When fitted the carb cables sit about 10mm behind the taps, but dead in line with the tap outlet spigot. Easy fix: Swap the taps right to left and left to right and the spigots now face forward out of the way. These turned out pretty good, but as I'm using pods I now have to make a rear support to support the carbs.

    Funny thing about right and left carb kits - they're not, only the idle screws are on different sides, everything else choke levers, fuel inlet spigot and mixture screw are all on the same side on both carbs.
    Attached Files

  • #2
    Attached Files


    • #3
      Looking good and much nicer than common flanged rubber boots.


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