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Thread: Mid-throttle carb syncing

  1. #1
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    Question Mid-throttle carb syncing

    Have just rebuilt my VM26SS carbs....'78 GS750E.
    Quick Q: Can I leave all carb tops off at the same time when adjusting slides if needed? (Thinking of possible air leakage down the slides affecting overall balance.....maybe over thinking it?? )
    I guess if the bench sync is good, the question could be moot, even though the bench sync is angled more to idle balance. Dunno.
    Last edited by Himble; 03-16-2021 at 05:45 AM.
    Cheers, Andy

    Current bikes... 78 GS750E, 72 CB500K1
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  2. #2
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    Default

    Overthinking.

    Remove all the tops, do the sync, put the tops back on.

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  3. #3
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    Default

    As already advised.
    Remove all carb tops , vac sync and refit them.
    Vac balancing is the only way to ensure all the cylinders are doing equal work.
    Bench syncing only aligns all the slides as a base line setting but in reality (except in a perfect world) just doing that will not ensure equal vac readings across all cylinders.
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  4. #4
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    And if you haven't already, get yourself a Morgan Carbtune. Simply the best.
    -Mal

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  5. #5
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    Thanks for all the replies. Will proceed to sync with all tops off!
    Cheers, Andy

    Current bikes... 78 GS750E, 72 CB500K1
    Previously owned...
    01 VFR800Fi, 67 Honda Sports 90
    71 Yamaha 175 CT2, 73 Yamaha RD250 (great bike!), 79 Yamaha XT250T
    75 Kawasaki KX125 (little screamer!)
    BMW R65, BMW R80, BMW R100LT

  6. #6
    KEITH KRAUSE's Avatar
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    Don't synch the carbs at "mid-throttle". There's no benefit as far as tuning. You can easily over-heat the bike too.
    Synch at about 2,000 rpm's unless your manual says otherwise. Adjust the rpm's by using the idle control knob underneath. It's much easier than using the throttle.
    Refer to the actual factory manual before you synch. I'm not positive, but I think your model specifies carb #3 as the "master carb" and it should be synched first and then you adjust the others to match it as close as you can. I may be wrong about it.
    And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
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