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Hitatchi HSC32 Carb wizardry

Discussion in 'XJ Technical Chat' started by Jadds, Apr 22, 2026.

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  1. Jadds

    Jadds Member

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    Quick question for the brains trust. with the intake butterfly closed, should it be a completely airtight seal?
    I have a very technical testing methodology for this. Seal intake around mouth and blow. Some of mine seem to be more airtight than others. Carbs have been rebuilt and butterflys are 100% from the carbs they came out of.
     
  2. Dan Gardner

    Dan Gardner Well-Known Member Premium Member

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    I’m no expert, so I may be corrected, but:

    no, the butterflies should not be air tight. They need to have a little bit of airflow to run. The trick is to synchronize them with their cylinder and the other four carbs and cylinders.

    the bench synch can be performed with a business card or paper clip or something to make sure they are slightly open the same amount after a rebuild or something. After the bench synch you need to do the running synch to compensate for variations in the cylinders.

    but the goal is definitely not a to have them air tight at idle
     
  3. Jadds

    Jadds Member

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    Thanks Dan, Thats what I had kind of assumed. There would need to be some air getting through.
    yep, not at the synch stage yet. still have a whole lotta building first.
     
  4. Brhatweed

    Brhatweed Well-Known Member

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    There's a good write-up on this on the tech section. Click on the XJ4Ever banner on the top right and go down to the Church Of Clean.
     
    biggs500 likes this.
  5. Jadds

    Jadds Member

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    thats a quality write up. Nothing else needed to learn about hitatchi HSC32 carbs.
     
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