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The reason YICS was not on later bikes

Discussion in 'XJ Technical Chat' started by LarryMc, Mar 20, 2018.

  1. LarryMc

    LarryMc Active Member

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    (copied article from internet)
    PERFORMANCE
    .....
    When the Fj600 came out in 1984 the engine wasn't just a bored out 550 varient. The combustion chambers shape was redesigned along with valve size, cam profile, timing curve and larger carbs with a differently designed airbox. The main goal was simply: performance.
    Even the fuel efficiency YICS system, designed to passify the EPA, was ditched when it was discovered that the bike pulled better without it dispite the decrease in fuel economy......

    Hmm?


    Could the YICS passage way be perminantly blocked if you want more from your engine?
    Leave the YICS tool in?
    All it would hurt is fuel mileage?
    Is the YICS system BS congered up to meet EPA requirements?
     
  2. k-moe

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

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    YIKES!: ALL ABOUT THE "YICS" SYSTEM.

    As scientific understanding improves, engineering practices also improve.
    As regulations change, the goalposts change as well.

    YICS met a need, and met that need as simply as possible given the constraints of the time.

    Make the engine better just by blocking off YICS? Well that depends on what the definition of better is.
     
    Last edited: Mar 20, 2018
  3. LarryMc

    LarryMc Active Member

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    I had viewed that link about a month ago and didn't think twice about it. Since I, just today, purchased 1984 Fj600 I was gathering more information on the bike and ran across the article that I quoted.
    Very true words on the definition of "whats better".
    YICS served its purpose, came and went just like "Toys R Us", the Ford Pinto, & Harvey Weinstein.
     
  4. Kickaha

    Kickaha Active Member Premium Member

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    No, it was a bored AND stroked variant
     
  5. Tim O

    Tim O Active Member

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    You could just never clean the YICS passages... self updating ;)
     
  6. MattiThundrrr

    MattiThundrrr Not a guru

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    If you leave the tool in, the seals will melt. There is a port block off you can install for permanent elimination. I doubt there would be a significant power gain.
     
  7. LarryMc

    LarryMc Active Member

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    I agree. It runs pretty sweet as is, why mess with it.
    The article got me thinking in that direction but my subconscious was saying "you know better than to f@¢k with this".
     
  8. Stumplifter

    Stumplifter Well-Known Member

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    :p
    So many times I should have listened to that little voice... that deep sinking feeling when things go off the tracks afterwards is always so humbling.
     
  9. Plug

    Plug Active Member

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    No truer words have ever been said!
     

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