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Thread: Carb adjustment question

  1. #1

    Default Carb adjustment question

    On the thread on Wet sumping, the conversation wandered to carb adjustment, so I thought it would be good to start a new thread.

    My initial question on the carb was: I just went to baseline the carb adjustments and was surprised what I found. The low-speed screw was only 7/8 of a turn open from seated. The high-speed screw was 1-7/8 turns open from seated. The baseline adjustments mentioned in the book are 4 and 1-1/2 turns, respectively. So the low-speed is set far leaner than the baseline, yet the plugs still fouled at idle. Has anyone seen adjustments this far away from the baseline?

    Cotten replied:
    Quote Originally Posted by T. Cotten View Post
    Lipdog!

    Please make certain that your LS needle is 3.5" long, the spring in the knob is on top of the needle, and the lift spring collar is in place with the flat side down.

    I send M344s out set at three and a half turns on the LS, and one and a half on the HS, but that assumes a sealed manifold assembly.

    ....Cotten
    I think everything checked out ok. Attached below are photos of both the high and low speed needles. The spring loaded ball on the LS side moves nicely too, and it looks like it was rebuilt and cleaned carefully in general.

    Given it seems to be fouling the (Autolite 303) plugs while idling (the bike is not registered/on the road yet) for 10 minutes, and the LS screw is only 7/8 of a turn out, do you recommend I start over at 3.5 turns for the LS and 1.5 turns for the HS, or would that just give me a richer idle and foul the plugs more?

    Thanks!
    Attached Images Attached Images

  2. #2
    Join Date
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    All carbs need to be adjusted for the motor.
    You need to read the part after initial adjustments & do those adjustments.TWICE!!!
    There is no setting that fits all motors & carbs.

  3. #3
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    I'd first measure the 303s for resistance, Lipdog.

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

  4. #4
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    303 is resistor copper core
    Starklite calls for their Indian script = NGK B7HS or Champion J6..non resistor plugs
    I hate Autolite plugs

  5. #5
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    Quote Originally Posted by duffeycycles View Post
    303 is resistor copper core
    Starklite calls for their Indian script = NGK B7HS or Champion J6..non resistor plugs
    I hate Autolite plugs
    I just hate resistor plugs, Duffey!

    Or at least all of my coils do...

    ...Cotten
    PS: Lipdog!
    Lots of 'rebuilt and cleaned' carbs crossed my benches (back when I was accepting new accounts).
    The 'professional' "rebuilds" often weren't.
    Please inspect the gallery plugs, as one ebay hero was selling kits with set screws, allowing both fuel and air to the wrong places.
    Last edited by T. Cotten; 09-19-2019 at 01:09 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  6. #6

    Default

    I have a box of NOS J6 plugs so I will swap them in. I will also check to see if there is a wet sump condition and check for manifold leaks. I am thinking I should start from the benchmark that Cotton recommends (3.5 turns out LS/1.5 turns out HS) and work from there.

    Cotton: I looked on a number of diagrams (like this one: https://www.jerrygreersengineering.c...y=1952&m=Chief) and can't find parts called the gallery plugs. Is there another name and are they on this diagram?

    Thanks!

  7. #7
    Join Date
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    They're just "plugs", Lipdog,

    #1 on Greer's list, Indian OEM 102420

    They plug galleries, and your M344 would have four.

    I'd post a pic of the crappy kit with set screws and other issues, but the vendor isn't here to defend himself.

    ....Cotten
    PS: Wow, mine just went up a buck, thanks!
    Last edited by T. Cotten; 09-19-2019 at 02:48 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  8. #8
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    Jul 2010
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    Quote Originally Posted by T. Cotten View Post
    I just hate resistor plugs, Duffey!

    Or at least all of my coils
    Whoa... 303 Autolite plugs work well in my Chief...don’t go bad mouthin’ my plug choice!

    In spite of two of the most knowledgeable vintage bike guys you’re likely to ever hear from, and they may be right, Lipdog...I’m thinking you just need to be patient. Slap a plate on that Chief and ride it under load for a while...see what’s up. You can chase problems all day long but without actually running the road, under load at more than an idle, I don’t think you’ll ever get an accurate picture what you’ve got going. Don’t go chasing a problem until you find out that you DO have a problem.
    Pisten Bulley is Harry Roberts in Vermont.

  9. #9

    Default

    Yeah, I get your point about chasing problems. But I don't think this carb is right. I swapped in the J6's, drained the excess oil from the sump, and got it started (for the first time, hot as well as cold). When I turned the LS needle in all the way, the bike still ran ok. Revving it a bit and checking the HS needle, it didn't seem to have much of an effect. And it fouled the plugs after a few minutes (see photo). I pulled the carb and will check the manifold for leaks this weekend, just to be sure.

    IMG_0366.jpg
    IMG_0369.jpg
    IMG_0370.jpg

  10. #10
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    And don't forget to check the length of both high and low speed needles, as various types are out there and small differences have a big effect.

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