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Thread: Harley 1912 single

  1. #1

    Default Harley 1912 single

    hello from France
    I just finish re-building of Harley 1912 single
    while most of the parts was original I try to respect and keep same look
    was difficult (and I am still not very happy with) for the gas tank (mix of repro/original) maybe at a time and by chance I can find an original one !!!
    I install accessories like I think some do it at that time , front and rear lamp,horn)
    i make some job inside the engine (new piston, re-boring, bushings ..)
    Bike is running smoothly now
    very special to drivehd12.jpgklax1.jpgDSC09294.jpgsargent padlock 1.jpg
    best regards from France
    Philippe

  2. #2
    Join Date
    Oct 2013
    Location
    Maryland
    Posts
    278

    Default

    Nice job, Philippe! Looks great!

    Dale

  3. #3

    Default

    Thank you
    I have a question
    when the engine is running , I see some (mixture) pushed out of bottom hole of the schebler carb
    I double check valve timing , intake valve seat and ignition ,everything looks good
    normally it should be no pressure (valve closed) or depression (valve inside ) inside this piping ? right?
    anyone already experience that?
    could be the intake valve spring? (it's new one)

  4. #4
    Join Date
    Sep 2005
    Location
    Sarasota, Florida
    Posts
    4,176

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    Your 1912 Harley is stunning, Philippe, and I admire the careful work you did to keep it so genuine. In regards to your Schebler; could it be as simple as the gasket between the bowl stem, and bowl ?
    Eric Smith
    AMCA #886

  5. #5
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,339

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    Philippe!

    Air enters the carburetor primarily at the bottom of the bowlstem, with metered air entering the airvalve with the poppet and spring (and then auxillary air "at high speeds" through a thumbtab, if it has one) .
    Although there were many sizes of springs, they are graciously adjustable.

    I set the initial spring tension as forum member Tommo has taught: a three ounce weight is placed upon the valve with the adjusting screw in the middle of its travel. The nut on the shaft is then set where the assembly is "weightless".
    The adjusting screw can then be used to tune the airvalve while running.

    More likely, however, is that there is too high of a level of fuel in the bowl. (There are no gaskets to the bowlstem bore.)
    Are you using a float of ~3 grams?
    Some modern floats are boatanchors.

    ....Cotten
    PS: I greatly appreciate that you "conserved" the machine, rather than "restored".
    Attached Images Attached Images
    Last edited by T. Cotten; 10-19-2019 at 11:07 AM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  6. #6
    Join Date
    Sep 2016
    Location
    Oregon
    Posts
    96

    Default

    great looking '12

  7. #7

    Default

    hi
    thanks for reply! one more good information to adjust or prepare a new spring , appreciate !
    my thinking was : assuming that " negative pressure" (little vacuum) is all inside intake piping when piston go down and open" automatic" intake valve and no pressure when valve close , it should,nt be possible to see mixture pushed out , right ?

  8. #8
    Join Date
    Sep 2005
    Location
    Sarasota, Florida
    Posts
    4,176

    Default

    I was referring to gasket 'N' which seals the bowl to the stem.
    Attached Images Attached Images
    Eric Smith
    AMCA #886

  9. #9
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,339

    Default

    We shall have language difficulties, Philippe!

    Vacuum in the manifold and carburetor is greatest at low RPM (although damage from a vacuum leak is greatest at high RPM).

    Air pulled upward by the motor should keep the bowlstem bore (the effective '"venturi"' of an HX design) reasonably dry.
    Raw fuel would suggest overflow through the 'needle valve guide' ("X"), the only path for fuel from the bowl.

    If the motor is not running, gravity does the rest.

    ....Cotten
    PS: Spitting because of "reversion" within the intake on a fresh motor shouldn't happen.
    (Except maybe with late OHVs with rad aftermarket cams, etc., of course.)
    Last edited by T. Cotten; 10-19-2019 at 02:51 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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