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Thread: 1940 and up intake nipple

  1. #1
    Join Date
    Jan 2006
    Location
    Menomonie, WI
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    1,274

    Default 1940 and up intake nipple

    Who makes a good intake nipple for a big port knucklehead. Part number 27039-40. I need a pair of them.

    Jerry

  2. #2

    Default

    Not sure if this is what you mean
    I replaced the nipples in the head. I got Carl Olsen ( http://www.carlscyclesupply.com/ ) longer ones that had to be fitted to the heads. Turned out to be quite a job to get the old one out and clean up the threads, had to pless a friend and he made a special tool. But all in all these and Cotton peek mainfold seals were just the ticket. Both spark plugs burning at the same color
    Hope this helps
    W

  3. #3
    Join Date
    Apr 2010
    Posts
    1,124

    Default

    Jerry,Did that job last year,The colony[vtwin]are very loose threads-I reordered from Carl,Carl's aren't much better-very loose-I had an NOS to compare and it was snug
    I was pissed the quality was so poor
    Roger

  4. #4
    Join Date
    Apr 2008
    Location
    Upper Yarra Valley, Victoria. Australia
    Posts
    896

    Default

    Hey Roger.
    If you still have the NOS unit, can you measure the major diam of the NOS thread and the aftermarket threads and post the readings here?
    Regards Steve
    Steve Little
    Upper Yarra Valley. Victoria.
    Australia.
    AMCA member 1950

  5. #5
    Join Date
    Apr 2010
    Posts
    1,124

    Default

    Steve,The only repro that I have came out of the motor,longer than original-They leaked bad-supposedly recently built by the best Harley mechanic in Texas!!![less than 500 miles] 1.740 thread od the original is 1.747
    The original has rounded edge to the thread and the repop are very pointy-much deeper cut
    If you hold them to each other and look into the light you can see lots of light because the repop is cut so deep,so it is more than the OD of the threads that are wrong
    [or my original is an oversize that fit nice!]
    You could help the Knuck world if you made better inserts
    http://www.caimag.com/forum/showthre...ad+intake+leak
    Last edited by duffeycycles; 03-15-2015 at 11:51 AM.

  6. #6
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
    Posts
    4,341

    Default

    Roger!

    Please do not forget that it is not the threads that seal, but where the shoulder butts up against the thin lip on the head casting. If that lip is damaged, it can be quite an issue.
    I have used nipples from several sources, but nearly always had to shorten the threads with the lathe. The only problem nipples I just couldn't use were Colony's with too large of a champher on the ID where the manifold ferrule seals.

    ....Cotten
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  7. #7
    Join Date
    Apr 2010
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    1,124

    Default

    I agree, the colony I ordered got sent back.The threads are not the seal but they are important.
    Loose crappy cut threads like the ones on an India made Royal Enfield fall apart.
    The rivet quality is also an issue.The Colony rivets are too hard

  8. #8
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
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    Roger!

    The Colony rivets are not too hard for a simple hammer-smack, but far, FAR too fat!

    Since no two holes will be the same, rivets must be cut individually to fit a reamed-to-clean hole, and with a tapered head as I described at http://virtualindian.org/11techleaktest.html.

    How on Earth anyone expects a flat-headed rivet to seal upon a round ID is beyond me, but the H-D and Indian factories probably depended upon dedicated tooling with monstrous press pressure.

    ....Cotten
    Last edited by T. Cotten; 03-15-2015 at 02:30 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  9. #9
    Join Date
    Apr 2010
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    Default

    I was told by a couple old Knuck builders that the Colony rivets were much harder than the originals and that combined with the smack method caused many heads with broken rivet holes,as the one I was doing had-I was told not to use them

  10. #10
    Join Date
    Jun 2001
    Location
    Central Illinois, USA
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    Roger!

    The bottom line is that the Colony rivets should be avoided entirely, for a variety of reasons.

    Their O-ring nipple seals are another example.

    ...Cotten
    Last edited by T. Cotten; 03-15-2015 at 03:59 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

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