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Fresh carb rebuild question

Discussion in 'XJ Technical Chat' started by Mechanic1978, Jul 2, 2021.

  1. Mechanic1978

    Mechanic1978 Active Member

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    hey all, just completed a fresh bs28 mikuni carb rebuild, was missing carb base #1 but thanks to Hogfiddles that has been resolved. (Thanks a million Hog!) My question is concerning the "yics" I just mounted them into the boots and I'm about to start the adjustments in the morning, but was concerned weather I will need to block the yics system first? I have my pilot air screws set at 2 1/2 turns out to start. Do I need to do the block off to get this adjustment done? I'm a master auto mechanic, and father was at a business called "CarburetorExchange" in Indianapolis for 40 yrs and I grew up building carbs and such. So I'm familiar with tuning but this is my first Yics engine. So before the headaches start figured I would brush up on your knowledge.
     
  2. hogfiddles

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

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    there are differing opinions on this........there are plenty that say it MUST be used, and there are plenty that say you don’t need to use it. personally, I don’t see a need for it unless you’re a track star and need to wring out that last Nth of a second to win. I have a YICS tool.....it’s still in the plastic pouch that it came in about 15 hrs ago....I don’t use it at all. No need. But, you read all the replies that come in soon, and then decide what you’re gonna do.

    dfox
     
  3. Mechanic1978

    Mechanic1978 Active Member

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    Appreciate the input.... Will do.
     
  4. Minimutly

    Minimutly Well-Known Member

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    If you were a track star you even more wouldn't use it, it would add nothing to your lap times.
    Leave it in the box.
     
  5. JCH

    JCH Active Member

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    I used a piece of vacuum hose and lubed it well... and that blocked off the little YICS ports and the hose didn't overheat or damage anything like that while idling , didn't notice any difference with or without hose blocking the ports doing the sync setting.
    I don't understand the difference in opinions on this topic and they are from the brightest members on this site too LOL... best advice do your own testing and decide.
     
  6. tabaka45

    tabaka45 Well-Known Member

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    I have one an I used it and I have no idea if it did any good. Haven't used it since and I can't tell any difference.
     
  7. Mechanic1978

    Mechanic1978 Active Member

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    Lol I planned to start this morning, but holiday is not playing nice....

    I understand the reasoning behind it. my 2cent.....
    If you have a chamber that all cylinders can pull from, then when one closes an another opens and partially pulls mixture from it and repeat, then it would (in theory) make sense to block it to fine tune each cylinder. But I feel that it won't be much of an issue, so when this holiday celebrations are over I will tackle it.

    Thanks everyone for your thought and input... Have a good 4TH!!
     

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