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heat question

Discussion in 'XJ Technical Chat' started by patrickw, May 31, 2014.

  1. patrickw

    patrickw New Member

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    So I was wondering if you could use an infrared temperature gun to get my fuel/air mixture close until I get a colortune. Here is my theory could be some crazy ramblings. So when your bike is up to temp you should be use the infrared thermometer to see what the temps are on each header pipe. They should be roughly the same maybe a degree or two off. If you have one that is hotter than the rest say one at 355 f and the other three are at 345. That would mean that one is lean. Just a thought I have a thermometer just waiting for payday to get the colortune. I don't think it matters but the bike is a 1980 yamaha xj650.
     
  2. MiCarl

    MiCarl Active Member

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    Or maybe the other three are rich......

    Or maybe that one is lean and the other three are rich......

    Or maybe it's like that because they're not synced........


    Comparison type measurements only have value if you know what you're comparing to.
     
  3. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Exhaust temp will vary from cylinder to cylinder based on more than how rich or lean it is; sync can be a factor as can valve adjustment.

    The ColorTune is only for mixture tweaking.

    AFTER you get a nice solid running vacuum sync. Set all the mixture screws at 2 1/2 or 3 turns out, and work on your vacuum sync.
     
  4. patrickw

    patrickw New Member

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    Yea that's what I was thinking. I will just wait. My screws are at 2 1/2 out. Thanks for the input.
     
  5. Polock

    Polock Well-Known Member

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    in theory it would work, airplanes use egt for mixture. i think 5 or 10 degree change is a little to much to ask for.
    i'll try it, just did the valves, synced, and set the mixture by ear. i have to find my temp gun
     
  6. Polock

    Polock Well-Known Member

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    i found it !
    warmed up till my temp gauge registered 180
    1...574
    2...555
    3...500
    4...520
    then just because i put the choke on till i just started to lift the plungers
    1...558
    2...580
    3...540
    4...560
    what's all that mean? i dono, i'am not changing anything
     

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