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Amal needle jet size

Discussion in 'Triumph (Classic)' started by lazyeye6, Apr 29, 2019.

  1. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    I have a 1970 Triumph Tiger (TR6R). I haven't been into the carburetor for
    10 years, so I pulled it apart to clean, inspect and clear the idle circuit.
    I had this a new chrome slide installed 10 years ago. It has performed
    faultlessly since then. I found that it had a 106 needle jet installed and on
    reviewing the service manual found that the specified needle jet is 107.
    As I said, it starts easily and runs nicely with no coughing or stumbling.
    The spark plugs are a darker brown than the tan color I would want, suggesting
    a dry carbon buildup. So I'm thinking it may be running a bit rich. I could
    adjust that with the air screw. The needle clip is on the center (2nd) notch.
    I would think that the 107 jet would make it run even richer. Anyone have
    any thoughts on how this carb is or should be set up?
     
  2. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    .106 from 1970 according to the parts books.
     
  3. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
  4. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    Thank you. So much for the specifications listed in my 1970 Service Manual.
     
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Sadly not uncommon!

    Factory manual for T140E models is all over the place with regards to carb settings!
     
  6. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    OK, all back together with the 106 needle jet and bike runs flawlessly. I shouldn't
    need to pull the carb apart again for another 10 years when I undoubtedly will ask
    the same question. :confused:
     
  7. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    OK, it isn't 10 years later, but I began having trouble with the slide on my carb sticking open. So I opted to buy
    my Tiger a new Mark 1 Amal. A 930. It came set up as per the specs as follows: 230 main, 106 needle jet, Std needle,
    needle position: 2 (middle notch), slide: 3 1/2.

    Got it dialed in and went for a test ride. It is snappy, no coughing and everything I could ask for. EXCEPT that it bogs down
    on WOT and then accelerates when I let off the gas. The plugs have perfect light tan/gray color, the air filter is OEM and
    clean. I had disassembled and cleaned all of the swarf out of this new-in-the-box carb before reassembly and mounting.

    Common wisdom suggests I should put in a smaller sized main jet. But what size? Buy a bunch of sizes until I get it right?
    Anything else I should look at?
     
  8. texasSlick

    texasSlick VIP MEMBER

    Joined:
    Jan 2, 2013
    I am thinking that you might be running out of gas at WOT. Possible cause could be clogged screens in fuel tap or needle seat banjo, or too small a main jet.

    Slick
     
    baz likes this.
  9. lazyeye6

    lazyeye6

    Joined:
    Feb 28, 2014
    I hadn't thought that a possibility. Certainly with the precious carb with identical set up, same taps and same banjo there was no bog down at WOT.
    Will try with both taps open to see if that has any effect.
     

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