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  1. #1
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    Default mikuni carbs on old iron?

    Hi,

    I'm thinking of installing a mikuni VM round side on my 74ci UL...
    I'm confused about the correct diameter, between 34, 36 and 38mm?

    Seems the 34mm is very popular for the 45ci so I tend to think the 38 would be a good choice for the big twin, but I see a kit which is supposed to fit both engine Vt No: 35-0107 and it confuses me a bit, I know you can change jets but is 34mm enough to feed a UL? Or I should go for a 38mm using adapter VT No: 35-0271 and get a VM38 (doesn't seem to exist a kit)

    Did anyone run a mikuni on a big twin flathead?
    What was your set up and jets?

  2. #2

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    A 38mm is the size mostly used on pans & shovels. If your intake manifold bore is large enough, that would be what I would use. There used to be 4 screw manifold adapters for the stock pan manifolds and the 38mm carb. Would that fit your existing manifold?

    Jim

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    Hi Jim,
    Yeah I saw that that's why I'm thinking 38mm should be better as we're talking about the same displacemnt as a FL pan or a Shovel, but then when I read the description of that 34mm kit from V-twin No: 35-0107 and they say it fits UL and WL it brought me doubt.
    My manifold is 3 bolts on the UL, not sure of the diameter tho, will have to check that, maybe that will help also.
    Did H-D made the 3 bolt manifold in different diameters? (there were oem on UL and WL)

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    Looking at my Palmer's, it looks like the Us and many of the Ws used 1 1/4 Linkerts, and that is approximately 32mm. So that should be sufficient unless you are trying to go fast.

    Jim

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    Actually harley 45s had 3 differrent diameters. The G motors had a small manifold. WLs had bigger manifolds and the WR and WLDR had the biggest.

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    Quote Originally Posted by JBinNC View Post
    Looking at my Palmer's, it looks like the Us and many of the Ws used 1 1/4 Linkerts, and that is approximately 32mm. So that should be sufficient unless you are trying to go fast.

    Jim

    Quote Originally Posted by flatman View Post
    Actually harley 45s had 3 differrent diameters. The G motors had a small manifold. WLs had bigger manifolds and the WR and WLDR had the biggest.
    Very interesting...
    Originally the UL had a M51, does it have a throat of 1"1/4 too?

  7. #7

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    Quote Originally Posted by ElekVins View Post
    Very interesting...
    Originally the UL had a M51, does it have a throat of 1"1/4 too?
    Apparently, yes, all the Us.

    Jim

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    ok, so the 34mm sounds good enough and the kit makes sense.
    I don't plan on racing it lol

    Thanks!

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    Well... before ordering a 34mm I mesured the diameter of my intake - couldn't get my caliper between the cylinder so I used a very high tech toothpick... - turns out it's 37mm (1"7/16) so I'm more leaning toward a 38mm carb now...
    (plus the hole has a groove at the entrance, which is about 40mm diameter (linkert has that same groove to go in, when the V-twin adapter is flat on that side)

    V-twin also sells a kit in 38mm, a Dell'Orto this time (is dell'orto better than mikuni?), who's supposed to fit
    G 1937-1963
    UL 1937-1948
    WL 1937-1952

    45ci if you have a WR manifold...

    VT No: 35-0059


    What you guys think?

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    38mm would be well suited for the U's ...

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    Quote Originally Posted by Dragstews View Post
    38mm would be well suited for the U's ...
    Dell'orto 38mm is on the way...
    Will let you know how it goes.

    Thanks everybody!

  12. #12

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    Get a 3 hole linkert adapter from kiwi indian, use a reversed shovelhead throttle cable. google vm38/9 and buy the carb only , I run one on my 38u.

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