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  1. #1
    CB750 Member Jwc1198's Avatar
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    Dec 2017
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    I donít know what to do...

    I am currently having troubles getting my 77 cb750 to keep running. It all started when I replaced the grips on the bike. After I did that the bike would run but bog out on me after just riding down the street. Iím not a mechanic of any sort so I was thinking it was dying because the carbs needed to be adjusted so I started messing with the pilot screws. I turned them all the way in and backed them out 1 3/4 turn and it would run better and I could ride farther than down the street but it still dies on me. At the same time I canít get full throttle.

    Iím honestly puzzled right now. But donít want to give up on the thing. Can anybody possible help me?

  2. #2
    CB750 Member jimmbo62's Avatar
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    Quote Originally Posted by Jwc1198 View Post
    I am currently having troubles getting my 77 cb750 to keep running. It all started when I replaced the grips on the bike. After I did that the bike would run but bog out on me after just riding down the street. Iím not a mechanic of any sort so I was thinking it was dying because the carbs needed to be adjusted so I started messing with the pilot screws. I turned them all the way in and backed them out 1 3/4 turn and it would run better and I could ride farther than down the street but it still dies on me. At the same time I canít get full throttle.

    Iím honestly puzzled right now. But donít want to give up on the thing. Can anybody possible help me?
    I had a similar problem and it was the strainer at the petcock. Would idle fine but bog down 4-5 minutes down the road. Have you checked the throttle tube for damage as well since it all started when you changed the grip?

    Sent from my SM-G950F using Tapatalk

  3. #3
    CB750 Member AwesomeCB's Avatar
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    Oct 2017
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    It's seems logical but who knows if I'm right?

    Quote Originally Posted by Jwc1198 View Post
    I am currently having troubles getting my 77 cb750 to keep running. It all started when I replaced the grips on the bike.
    When you replaced the grip on the throttle side, you might have done something to affect either the push or pull throttle cables. The cables attached to the white plastic throttle pipe and it conceivably you may have twisted, kinked (whatever) one of those cables. Did you unscrew the switch and housing that covers the end of the throttle pipe and maybe not reseat the switch properly?

    I dunno, but logically, if the problem started when you changed the grip, something must have happened then. Messing with anything on the other end of those cables doesn't make sense if you never touched them to begin with. If you're able to get things at the carbs etc. set back to where they were when the bike was running fine, go back and recheck the throttle grip and cable ends. The problem you have now is even if the throttle end is okay, you probablly messed up the carb settings on the other end and you'll have similar problems as before.

  4. #4
    CB750 Member Geezerbiker's Avatar
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    Feb 2018
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    Willamina, OR
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    The next time it acts up, open then close the gas cap. If that makes it run better for a short time, the vent is plugged.

    Tony

  5. #5
    CB750 Guru amc49's Avatar
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    Sep 2015
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    Better, leave it cracked open for a bit but don't stab brakes to make the fuel slosh.

    Pay attention to that strainer comment higher up. Honda changed the early DOHC petcock away from the standard one used on the SOHC as well, the passages were too small for the fuel flow needed under certain conditions. I have had flow issues even on my CB550 because of pressure issues due to the same small size of the petcock channels. Even with a well open vent it can require a certain head amount of pressure to purge all the passages with fuel and even more critical on a low tank level. When mine showed up, a full tank stopped it instantly but only after waiting a minute or so for the fuel to purge with the added weight.

    The later DOHCs had more trouble as the higher performance required more fuel and the petcocks changed more than once, each time getting bigger passages inside them.

  6. #6
    CB750 Addict madmtnmotors's Avatar
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    Apr 2015
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    I think this was resolved on another forum. He had dislodged one of the throttle cables or choke cable IIRC
    I know, I know, "everybody else is doing that way"...

    High price to pay for being "stylish"...

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