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fuel coming from vacuum port on petcock

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    fuel coming from vacuum port on petcock

    Hi All,

    I've been diagnosing a rich condition. Adjusted float bowls. Check.

    To balance the carbs, I removed the fuel tank and rigged it next to the bike so I could get at the balance screw. I used new lengths of see through fuel line. Once I got it started I saw that fuel was actually coming from the petcock vacuum port and running into the left carburetor. That seems like a likely cause of a rich mixture.

    I removed the vacuum line from the left carb, plugged the hole with my finger, and put the petcock on prime. The bike really seemed to settle down. The idle was much more controllable.

    Something I noticed is that air is blowing OUT of the vacuum port on the carb. I would remove my finger slightly and feel the pressure.

    So, two questions: Does it seem like a bad petcock? Is the vacuum port from the carb acting normally?

    Thanks as always,
    Matt

    #2
    Originally posted by matt_gs450 View Post
    Hi All,




    So, two questions: Does it seem like a bad petcock? Is the vacuum port from the carb acting normally?

    Thanks as always,
    Matt
    Bad petcock, check. Vacuum port, it is just a passage for air to flow, working normal, check.

    Comment


      #3
      Thank you waterman.

      Looks like I'm ordering a new petcock. Z1 has this one which claims to fit my bike:
      Z1 Enterprises specializes in quality Motorcycle parts for Honda, Kawasaki, Suzuki and Yamaha Classic Japanese motorcycles from the 1970's and 1980's.


      -Matt

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        #4
        Conclusion: new petcock = bike running fantastic.

        Comment


          #5
          Originally posted by matt_gs450 View Post
          Conclusion: new petcock = bike running fantastic.
          A new petcock was my first purchase when I got my bike. Then o-rings, then some carb dip, then an impact driver, then a valve cover gasket, then some tappet valve feeler gauges, then an air filter box, then.......oh heck, you get the idea.
          Larry D
          1980 GS450S
          1981 GS450S
          2003 Heritage Softtail

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