1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Running sync: screw in or out, that is the question

Discussion in 'XJ Technical Chat' started by quebecois59, Nov 10, 2015.

  1. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Ok. I will look through that and see if anything stands out. That will be a big help for me to examine for you.
     
  2. aliyanage

    aliyanage New Member

    Messages:
    7
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Switzerland
    wow thanks a lot for the help, I just made some videos which I will upload later may that helps too...
     
  3. Mechanic1978

    Mechanic1978 Active Member

    Messages:
    356
    Likes Received:
    107
    Trophy Points:
    43
    Location:
    NOYB
    for years now I have always set the quad vacuum gauges on the carb boot nipples and see what carb 3 is running at, if its high, ill lower it or vise versa to an acceptable range. then I just set the others to match it, once they all match I adjust the idle knob. syncing is fairly quick once the tank is off. any bike with a 4 carb setup i've done it this way with stellar results every time. I will also note, once the sync is matching, the pilot air screws may need to be tweaked. just because your pulling equal vacuum does not mean your running leaner or richer on one carb vs the other.

    Another note, at operating temp, you can use a infared thermometer to test the temp of each exhaust pipe right at the mounting flange for temp differences between cylinders, this is how we test and adjust final pilot air screws for ones running too rich and or lean. richer cylinders will run hotter from having more fuel in there to burn.
     
    Last edited: Jul 8, 2021
  4. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    This is incorrect. Richer mixture will burn cooler.
     
    Oblivion and hogfiddles like this.
  5. Mechanic1978

    Mechanic1978 Active Member

    Messages:
    356
    Likes Received:
    107
    Trophy Points:
    43
    Location:
    NOYB
    My bad that is incorrect, yes I meant cooler. Thanks for setting me straight there Simmy!
     
  6. Simmy

    Simmy Well-Known Member

    Messages:
    2,261
    Likes Received:
    1,126
    Trophy Points:
    113
    Location:
    Waterloo Ontario Canada
    I know you know your stuff, we all have brain farts.
     
    Mechanic1978 likes this.
  7. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    I don’t see in the pics where you disassembled the throttle linkage to replace the throttle shaft seals.
    -Did you do them?
    -Did you make sure to put the air jets under the diaphragm back in the proper positions (bigger number toward the front of the bike)? It wouldn’t be the first time that these got mixed up.
    -Did you make sure that the “36” air jets are all in the front of the rack?
    -Did you make sure that you didn’t inadvertently swap any of the main jets with any of the idle jets?
     
  8. Mad_Bohemian

    Mad_Bohemian Active Member

    Messages:
    744
    Likes Received:
    57
    Trophy Points:
    28
    Location:
    Ravenna MI
    Ok, So I thoroughly cleaned the carbs, back together and bench synced then put on the bike. I can get it to run by playing with the choke but if I just let it idle it will slowly die. Like I said, I did a bench sync on the carbs but have not done a running sync yet. Idle mixture screws are all 3 turns out. What do you guys recommend as the next step? I tried adjusting the idle setting (knob that adjust running idle) but she goes from slow die to increased RPMs. Should I back the idle air mixture down?? as always TIA
     
  9. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Idle speed screw only changes the speed.
    The balance screw are between the carbs, on the linkages.

    between 1-2 balances 1-2
    Between 3-4 balances 3-4
    Between 2-3 balances 1/2 with 3/4
     
  10. Mad_Bohemian

    Mad_Bohemian Active Member

    Messages:
    744
    Likes Received:
    57
    Trophy Points:
    28
    Location:
    Ravenna MI
    Yup, I got relationship down from studying the earlier posts here...
    So I should just work on the running sync first, then worry about idle air mix later?
     
  11. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Set all 4 mixture screws at 2.5 turns out for initial setting

    then start your bike and get it running and warmed up.

    when it’s adjust to a reasonable idle speed with the enricher off, shut it down and hook up your gauges to do the running sync.

    Then check mixture colors/temps and adjust mixture screws as needed.

    Re-check sync if you wish....

    sync, colortune, sync...... there you go:)

    do you still have VooDoo?? I thought you sold it awhile back..... I must have things mixed up a bit—-
     
    k-moe likes this.
  12. Mad_Bohemian

    Mad_Bohemian Active Member

    Messages:
    744
    Likes Received:
    57
    Trophy Points:
    28
    Location:
    Ravenna MI
    Thanks Hogfiddles Yup... still have VooDoo...she's the one givin' me fits with the carbs. I may have to pull them and run them through the ultrasonic cleaner. She'll fire up one time, then the next day she'll just thumb her nose at me and not fire up.... grrrr. Gonna get new plugs and see if that helps. I know this should be fairly easy to do, but I swear I could look at a smoothly idling bike, pick up a screw driver and THINK carb adjustment and the bike would start sputtering.... :p

    p.s. I don't have a colortune plug, is there one you recommend?

    p.p.s. What cleaning solution do you guys use in your ultrasonic cleaner??
     
  13. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Recommendations—

    Colortune - get the Gunson 14mm Colortune plug

    Ultrasonic - I don’t use one... I do each piece by hand
     
    Timbox and k-moe like this.
  14. Mad_Bohemian

    Mad_Bohemian Active Member

    Messages:
    744
    Likes Received:
    57
    Trophy Points:
    28
    Location:
    Ravenna MI
    Looks like the Gunson 14mm is not available and according to their website they don't know when it will be.... :(
     
  15. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Check with Len Chacal
     
  16. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

    Messages:
    19,613
    Likes Received:
    6,703
    Trophy Points:
    113
    Location:
    The City of Seven Hills
    You can get adaptors from Gunson to use the other size colortunes in a machine that has a 14mm plug.
     
  17. Mad_Bohemian

    Mad_Bohemian Active Member

    Messages:
    744
    Likes Received:
    57
    Trophy Points:
    28
    Location:
    Ravenna MI
    Chacal had it...it's on it's way....
     
    hogfiddles and k-moe like this.
  18. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

    Messages:
    14,626
    Likes Received:
    5,008
    Trophy Points:
    113
    Location:
    near utica, new york
    Of COURSE he did :)
     
    k-moe likes this.

Share This Page