CB550 fuel line
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CB550 fuel line

This is a discussion on CB550 fuel line within the Technical forums, part of the Caferacer.net Forums category; I just tried to hook up the fuel tank on my CB550 for the first time (intake manifold O rings finally arrived) and ran into ...

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Thread: CB550 fuel line

  1. #1
    Stattz's Avatar
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    CB550 fuel line

    I just tried to hook up the fuel tank on my CB550 for the first time (intake manifold O rings finally arrived) and ran into a couple of things:

    1. There appear to be two connections for fuel lines on the carb rack, one set a little higher than the other, but only one line coming from the tank. Which should I connect to, and what's the other for? (Gas spews put of somewhere if I turn it over with the line connected to the lower and larger diameter nipple.)

    2. How do I hook up the choke. My Clymer manual says nothing (that I can find) about the choke. I think I've found the right place to hook it up, but if I do it seems way to short and the choke is full on all the time with no way to adjust it. How should this be connected and does it need to happen before I slide the carbs all the way into place?


    Stattz

  2. #2
    Senior Member Geeto67's Avatar
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    1. cb550 carbs have a set of connections for fuel and another nozzel for vacum. hooking the fuel line to the vacum will cause the engine to flood with gas. The bigger one should be the fuel inlet. On the earlier cb550s the rack has two inlets for fuel side by side and two vacume outlets side by side. the fuel inlets are higher. you should be ablt to spin the motor with the e-starter and feel the vacume line sucking in if you are stuck.

    2. no clue without seeing the carbs. someone here owns a 78 perhaps they will chime in....or www.sohc4.us

    by the way make sure the cb550 carbs are back against the rubber manifolds. They have a ridge and you wil think they are in but they are not. The rubbers must be totally agains the rack back plate.


  3. #3
    Stattz's Avatar
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    Geeto,

    Can you clarify what you mean by "carbs are back against the rubber manifolds". Are you talking about the intake manifold rubber boots or the air filter rubber boots? Is the ridge the little lip-type thing on the intake side of the carbs for the boot tofit over. I did have a problem doing this, but seemed to get it on OK. What happens if it's not on right?

    Thanks for the prompt response. With luck it'll fire up tonight. I hope.


    Stattz

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  5. #4
    Stattz's Avatar
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    I appear to have worked it out. I hooked up the fuel line using the larger of the two nozzles and

    Lo! She runs!

    I didn't hook anything to the other nozzle and could feel no vacuum there.

    Fired right up, but is idling at around 4000rpm. The idle adjustment screw is set as low as possible, but makes no difference. Manually operating the choke lever slightly increases idle speed. What else is there to adjust?

    I still have a couple of hoses that I have no idea what the're for - one is the size of a carb overflow tube, the other slightly bigger. The last half an inch of he bigger one has a larger diameter, kind of like a boot cover for something. Hard to explain. Does anyone have any idea what it might be? It's too large a diameter for the other nozzle.

    Still, I'm feeling chuffed - she runs.

    Stattz

  6. #5
    Senior Member Geeto67's Avatar
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    quote:
    Geeto,

    Can you clarify what you mean by "carbs are back against the rubber manifolds". Are you talking about the intake manifold rubber boots or the air filter rubber boots? Is the ridge the little lip-type thing on the intake side of the carbs for the boot tofit over. I did have a problem doing this, but seemed to get it on OK. What happens if it's not on right?

    Thanks for the prompt response. With luck it'll fire up tonight. I hope.


    Stattz
    When pressing the carb rack into the intake manifold rubber boots (not the air cleaner) there is a raised ring around the carb. I see a lot of 550 owners who only push their carb rack till that raised ridge seats, not back all the way like they are supposed to. the intake rubber boots should be close if not up against the back of the carb rack backing plate. not pushing it in all the way will casue the bike to run lean and eventually burn a piston.

    You should have a nozzle sticking out of the bottom of each float bowl (the earlier 550s do, not sure about the later ones) these should have lines on them to drain overflowing gas somewhere else and not on the top of the engine. The onyl other line I can think of is the case breather for the crankcase. should be underneath the carbs on the case.

    congrads, it runs dude.


  7. #6
    Senior Member Geeto67's Avatar
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    quote:
    quote:
    Geeto,

    Can you clarify what you mean by "carbs are back against the rubber manifolds". Are you talking about the intake manifold rubber boots or the air filter rubber boots? Is the ridge the little lip-type thing on the intake side of the carbs for the boot tofit over. I did have a problem doing this, but seemed to get it on OK. What happens if it's not on right?

    Thanks for the prompt response. With luck it'll fire up tonight. I hope.


    Stattz
    When pressing the carb rack into the intake manifold rubber boots (not the air cleaner) there is a raised ring around the carb. I see a lot of 550 owners who only push their carb rack till that raised ridge seats, not back all the way like they are supposed to. the intake rubber boots should be close if not up against the back of the carb rack backing plate. not pushing it in all the way will cause the bike to run lean, which can mean a high idle, and eventually burn a piston. The adjsutments for the carb are the air (fuel) screws, the throttle belcrank and cable, and the slide height. it might be that your slide is too high, or the cabe is pulling it all the way open. I'm in foreign territory with 78 550 carbs so don't take everything I say as gospel.

    You should have a nozzle sticking out of the bottom of each float bowl (the earlier 550s do, not sure about the later ones) these should have lines on them to drain overflowing gas somewhere else and not on the top of the engine. The onyl other line I can think of is the case breather for the crankcase. should be underneath the carbs on the case.

    congrads, it runs dude.


  8. #7
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    Thanks Geeto, I'll investigate the air screws and slide. When I bought the bike the carb rack was removed with intake manifolds attached. Hence the missing nuts and O rings. I'll check to make sure the're seated properly in the boots.

    The carb overflows all have hoses as does the case breather. Hmmm.



    Stattz

  9. #8
    LiLBull's Avatar
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    Stattz also check out my response in the general forum for a micro fiche of your carbs to identify carb parts you maybe not familiar with. George


  10. #9
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    Thanks, all.

    Work is now in progress.

    Stattz

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