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1972 Combat. Setting the new 932 Amal Premier: a nightmare!

Discussion in 'Norton Commando Motorcycles (Classic)' started by pierodn, Apr 12, 2018.

  1. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi All.
    My cousin"s Combat is impossible to set with the new 932 18/19 Amal Premier (arrived with 106/230, 17 air pilot, needle in the center; but not with the cutted spray hood).
    I have several Commando all with the old carbs overhaulled and the bikes have a good idle and setting and run great.
    I think to be able with Amal concentric setting.
    This Combat, with old carbs overhaulled runned very well with good idle but my cousin has changed because has broken one flange to tight one manifold.
    The bike not only cannot have an idle but when go up with RPM doesnt go down soon and remains high for a while (there is not air leak).
    The only way to have a decent (not good) setting is to go with only half turn of the air unscrew from all tight .
    With 1 and 1/2 turn of air screw the bike go to 2000 RPM.
    The sliders are both syncronized with 5,5 mm of cut open.
    Amal says to fit 19 air pilot that will send me; i dont think this is the problem.
    I have well cleaned all the air and fuel ways and floats arrived setted like x manual.
    I cannot say that Premier are not good, even if i dont like to use, because i have mounted two pair to my friends bikes without problems.
    In the meanwhile i will fit two my old 932 overhaulled and i know the bike will run great.
    Sugests will be very apreciate.
    Thanks.
    Piero
     
    Last edited: Apr 12, 2018
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  2. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I just swapped out #17 pilot jets for #19 on my T120 and it is MUCH better. It is very clear that the #17s were far too weak.

    So I would at least hold fire with any other changes until you have tried the #19s.
     
  3. Steves

    Steves

    Joined:
    Oct 16, 2016
    And remember when you set the aircsrews and the rpm goes up then you reduce the rpm by adjusting the slide screws. It sounds like the slides are too high so the rpm takes awhile to reduce.

    So set the slides balanced giving 1200 rpm or so, adjust the airscrews to Increase the idle, then set slide screws to set 1200 rpm again, then idle screws to increase rpm (there may not be much change at this point). Then set idle about 900 rpm with slide screws, just be aware at this point you are making minute and even adjustments.

    And what Fast Eddie said.
     
  4. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    Sorry but the slides are not high.
    They are setted to 5,5 mm and usually a good idle is with 6 mm (a drill size).
     
  5. Steves

    Steves

    Joined:
    Oct 16, 2016
    Ok but to set correctly you set slides then pilot jet then slides then pilot jet etc. You cant just set the slides at a set height and leave them, the process involves adjusting both to get to the idle speed you want. Hope that makes sense.
     
  6. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Yes. Slides should be set slightly high, air screws then adjusted to the point where the tickover is fastest, then the slides are lowered until the desired idle speed is reached.

    All on a hot engine of course.

    There is no such thing as a ‘fixed’ or ‘standard’ slide height.
     
  7. gtiller

    gtiller VIP MEMBER

    Joined:
    Nov 5, 2012
    +1 with @Fast Eddie - get yourself a pair of number 19 pilot jets before you go any further!

    3DE8AC6A-90BC-429F-B6DF-BA7FECE66A4F.jpeg

    There has been some talk from Andover in recent months, and I think the beginnings of an official acknowledgement from Burlen Fuels (Amal) that maybe they need to consider shipping with a #19 pilot jet instead of a #17
     
  8. Madnorton

    Madnorton

    Joined:
    Jun 9, 2008
    Dumb question - you have remembered to fit the balance pipe or block the pipes on the manifolds. Slack cable at carb tops, you may have set it but check again. With the premiers it also easy to dislodge the needle in the clip when fitting the slide back into the body.
    The #19's are a leap forward, and just show what crap there was being made in the 70's on worn out machines, they were that slack tolerance wise they just over fueled the engine at most throttle positions.
     
  9. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    [QUHi.
    OTE="Fast Eddie, post: 370947, member: 5411"]Yes. Slides should be set slightly high, air screws then adjusted to the point where the tickover is fastest, then the slides are lowered until the desired idle speed is reached.

    All on a hot engine of course.

    There is no such thing as a ‘fixed’ or ‘standard’ slide height.[/QUOTE]

    Hi.
    Yes, 6 mm is slighyly high. But there is no idle the same! while You can find a good idle with 5,5.
    But the engine RPM, warm, remain 2000 rpm and when go down after a while doesnt have idle.
    I repeat, you can set a decent idle and the RPM that goes down quickly only with air screw closed (only half turn unscrewed from tight).
    Why???
    Can i try with the throttle needle one notch high?
    Please, dont let me know again how you set the carbs, my bikes have all old Amal and all run great with idle and good setting.
    Thank you.
    Piero
     
    Last edited: Apr 12, 2018
  10. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Changing the needle will not alter how the air screw works.

    The air screw is not working because the pilot jet is too small.

    Remember, the air screw controls the air, the pilot jet controls the fuel, they both supply the same chamber.

    Hence, if the pilot jet is too small, adjusting the air screw will have little, or no effect.

    Honestly, wait until until you have the #19s because whatever you change now, you will most likely change back again after fitting the #19s !
     
  11. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    I believe (although I cannot find them now) that there have been reports of Premier's shipped with main jets loose, or incorrect jets from the factory.
    And some have reported having to file some material off the mounting flanges so they don't interfere with each other. Maybe they are not sitting exactly flat, so not sealing?
     
  12. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    I forget to say that the spark plug are never brown but more white.
    Changed the 17 with 19 is better to go from 230 to 240/250 main jet?
    Thsnk you
    Piero
     
  13. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I can’t help with the main jet Piero.
     
  14. Steves

    Steves

    Joined:
    Oct 16, 2016
    Sounds like you need bigger pilot jet as per FastEddie. I run 220 mains on my combat, (sea level UK). I also use chamfered spray tubes, needle in the mid position. With flat top spray tubes I had the needle in bottom position (richer). 250 main sounds way to big but you will need to experiment for your bike and locale. Just make sure you get proper Amal jets then you stand a chance they are sized right! But I think you know all this stuff, oh for injectors an ECU and a laptop.
     
  15. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    That’s a good point ...
     
  16. Steves

    Steves

    Joined:
    Oct 16, 2016
    And as I have learnt a number of times through experience a fuel problem could (90% likely hood) be an electric (ignition) problem and vica versa. A couple of weeks ago a perceived oil burning problem I had turned out to be a duff coil!
     
  17. pierodn

    pierodn

    Joined:
    Nov 10, 2012
    Hi.
    My old stock Combat carbs have “cutted spray tubes”.
    This that i have ordered saying for Combat doest have and are flat!
    And arrived with 17 pilot air.
    I cannot understand why the supplier doesnt take a quality control!!!
    Piero
     
  18. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    Nothing to do with quality control.

    All 750 carbs had flat spray tubes (and 622/124 needles) as standard.

    The 17 pilot jet is Amal's standard size for Premier carbs, although it has been found that 19 is more suitable in some cases as already discussed.
     
  19. baz

    baz VIP MEMBER

    Joined:
    May 26, 2010
    As lab says it should have the flat top spray tube with a 2 ring needle,
    The 4 ring needle is used with the stepped spray tube
    I'd check everything on these carbs ,float height blockage etc.
    I don't know what the premier carbs are like but the ordinary concentric out of the box often had dwarf in them , wrong jets /needles etc etc also slides that were unfettled
    I used to think they were loosely assembled for the buyer to finish off!!
    At least with a premier you can take the pilot jet out and clean the port or change the size
     
  20. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Blaming dwarfs now eh Baz ?!
     
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