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  1. #1

    1980 CB750F -> Original Carbs Replaced w/1983 CB1000C Carbs / Fuel Delivery Question

    Getting my 1980 CB750F back on the road, well at least I'm trying. Probably haven't had it out for a ride since 1991 or so. Made a few attempts before but always got sidetracked for one reason or another. This time is different!

    Anyhow, the original CB750F carbs are being replaced (parts missing, bent needles, etc, etc) with a set of 1983 CB1000C carbs that I picked up from a friend. The CB1000C carbs have been gone through and are ready to go except for the fuel delivery system. The CB1000 carbs had the spawn of satin (SOS) contraption on them which is not going to be used. With that said, the CB1000C carbs have two fuel inlets vs one on the CB750F. Therefore I need to run the fuel line from the tank/petcock to the two fuel inlets. When replacing the SOS what should my fuel lines look like? Assuming I will need a "T" or a "Y" to split the fuel line from the tank to the fuels inlets on the carbs. Also, there is a potential for some tight bends in the fuel line.
    Does anyone have any pictures of their fuel line set up when replacing the SOS?

  2. #2
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Fort Worth TX.
    You will be making your own as nobody does that switch enough to tell you. You'll need to block off the vacuum nipple to the #2 carb that the others do not have. Your issue will be the angles like said, the later carbs split the lines to get fuel there faster as the early petcocks did not flow enough fuel and engine runs out when using engine hard. You will need a T or Y like you thought.

    The SOS was used when people refused to turn petcocks off when killing engines, then the carbs siphon fuel into engine to hydrolock it, you really DO need to train yourself to turn petcock off or trouble ahead.

  3. #3
    Thanks for the comments... The vacuum nipple is blocked off to the #2. I redid the fuel lines with a "T" above the #3 carb. Adjusted the petcock so the outlet is directed "in" like the stock version vs. towards the rear tire with the aftermarket petcock. With the smoothed out bends in the fuel line and the "T" connector it started up and ran which was the goal.

    With the engine running, I was able to blow out the sunflower seed hulls, and fluffy bedding that a mouse left in the Kerker many years ago!

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