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Retrofit Amal Premier pilot jets? (2016)

Discussion in 'Norton Commando Motorcycles (Classic)' started by grayluders, Feb 6, 2016.

  1. grayluders

    grayluders

    Joined:
    May 20, 2013
    I've removed the pilot circuit blanking plugs on my Amal 930s and pressed out the .016" pilot bushings, tapping the blanking plug passages 2BA.
    Is it possible to fit the Amal Premier pilot jets through these former blanking plug orifices?
    Would one choose an .015, a .017, or a .019" for today's fuel?
    If not possible, something else that could improve on the gol' darn .016 bushing?
    App is a '67 RE Interceptor.
    Thanks, and apologies for possibly dumbly lobbing a "oil thread" question out!
    Cheers,
    gl
     
  2. Jerry Doe

    Jerry Doe Admin

    Joined:
    May 21, 2003
    The Amal premiers come with a #17 pilot jet. I find these too lean with peashooters and use a #19.
    I am not sure about the first part of the question. Sounds a bit sketchy.

    Cheers
     
  3. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    That makes it unlikely anyone knows an ideal size for an alternative pilot jet.

    But as you are not happy with the standard size, is that because you think it is too big or too small? Is it passing too much fuel or not enough?
     
  4. Jerry Doe

    Jerry Doe Admin

    Joined:
    May 21, 2003
    For my bike it is running to lean with a #17.
     
  5. grayluders

    grayluders

    Joined:
    May 20, 2013
    Thanks - real issue is viability of using Premier external pilot jets in lieu of the pressed-in bushing.
    Just hypothesizing that, given that original pressed-in bushing is a wimpy .016", and the premier jets range considerably larger, that there is an opportunity to compensate for today's "different" fuel.
    gl
    (who has a Combat fitted with a 34mm Mikuni, thank you)
     
  6. htown16

    htown16 VIP MEMBER

    Joined:
    Apr 29, 2009
    Instead of switching to the #19 couldn't you just turn the air screw in a little bit?
     
  7. toppy

    toppy

    Joined:
    Dec 2, 2012
    My air screws (with premieres) are three quarters of a turn out. I wondered why as the bike will not idle or start on the more normal one an half turn (starting point) now I can see why.
     
  8. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    You make that sound like a lot less trouble.
     
  9. RoadScholar

    RoadScholar VIP MEMBER

    Joined:
    Dec 28, 2008
    I have a '67 RE Mk1a that came with a new set of still-in-the-box 930s that were jetted according to the work shop manual; I have the air screws out about 2 turns and it runs fine with 93 R+M/2 E10 (sign on pump says MAY CONTAIN up to 10%).

    The Premier pilot jets won't fit, but, probably, could be made to, the architecture is essentially the same. New Amal concentrics are relative cheap and function very well if you add a chrome sides, or just purchase the Premiers and go worry about something else...

    If you pursue the implementation of the Premier pilot jets into your 930s, please add some pictures, and best wishes.
     
  10. ag12680

    ag12680

    Joined:
    Sep 23, 2013
    I have the same question. I'm running peashooters with new Amal Premiers + K&N on my MkIII and getting midrange popping. 1.5 turns out on the air screws.
     
  11. pete.v

    pete.v

    Joined:
    Oct 31, 2009
    Yes you can but you can only go so far to where air screw position doesn't make a difference and the jet will need to be sized. If you are just too darn lean you could screw it in all the way and it won't respond of if too rich and/or blocked you could unscrew it completely without change.
     
  12. Nater_Potater

    Nater_Potater VIP MEMBER

    Joined:
    Apr 7, 2013
    Okay for idle, but the pilot jet affects operation into slide cutaway/needle realm, so you're primarily running on the pilot jet during a steady-throttle cruise. This has a direct bearing on fuel mileage, also.

    Nathan
     
  13. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009

    How far open is the throttle in your "midrange?"
     
  14. Jerry Doe

    Jerry Doe Admin

    Joined:
    May 21, 2003
    I have Toga peashooters on a Standard MK3. I had to put #19 pilots in and raise needle 1 notch. I cannot remember what size mains I ended up with...
     
  15. htown16

    htown16 VIP MEMBER

    Joined:
    Apr 29, 2009
    I've put on two sets of Premiers and all four had fuel levels more than .27 below the float bowl top, Amal's recommended minimum. This is measured with a u-tube at the middle of the carb. If you suspect leaness this is another variable to check.
     
  16. grayluders

    grayluders

    Joined:
    May 20, 2013
    After no response from Burlen or several other chat groups I'd posted to, until your message, I ordered a pair of .019 Premier jets, and a pair of earlier Concentric .025 jets, the ones that thread in to the front flange transfer port from the float bowl.
    So we'll see what, if anything, can be made to work.
    Did find on an archived Triumph chat group discussion that the earlier front idle jets may not work if the carb bodies were originally for two versus four-stroke applications - why we don't know, presumably something in the transfer passages.
    At the very least, the idiot pressed-in bushings can always be reinserted, and I'll have cut-off air screws threaded in to the former plugged passages for cleaning.
    Will report back later.
    Cheers,
    gl
     
  17. kommando

    kommando

    Joined:
    May 7, 2005
    The earlier 25 marked pilot jets are 17 thou, and cleaned out using a 16 thou drill.
     
  18. mschmitz57

    mschmitz57

    Joined:
    Feb 13, 2013
    I see Old Britt's sell the elusive Amal Premier pilot jets in various sizes. $25 each!
    A little precision drill bit is pretty cheap. I think I'd try drilling my removable jets slightly larger before I'd pay 50 bucks for 2 new ones, but then I'm pretty cheap.
    What could possibly go wrong?
    go wrong?
    o wrong?
    wrong?
    wrong?
    rong?

    I have 2 new (untested) 930 Premiers on my Atlas so I may put this to the test.

    https://www.oldbritts.com/ob_1830.htm
     
  19. grayluders

    grayluders

    Joined:
    May 20, 2013
    Here's a link to a Triumphrat discussion, in which Phil Beresford of Burlen explains quite a bit, and includes a cutaway photo
    http://www.triumphrat.net/classic-vinta ... ost2957057

    I separately just heard from Mr. Beresford, who wrote: "The Premier carburetter bodies are machined differently to provide a seat for the taper of the Premier Pilot Jet."
    This taper shows in the photo mentioned above.

    Unless I can establish a good taper for a Premier jet (lapping with an old pilot bushing brazed to a spindle?), looking more like trying a jet threaded at the front flange transfer port makes more practical sense.
    gl
     
  20. ag12680

    ag12680

    Joined:
    Sep 23, 2013
    By midrange I mean 2-3K RPM. I have 260 mains and moved the needle all the way up (clip in bottom notch). Still not sure why the pilot jet can't be addressed with the air screw.

    Almost have the brakes done so I can actually ride and see what the motor does under load.

    Thanks guys,

    Andy --
     

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