78 GS750 Petcock

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  • Guest

    #1

    78 GS750 Petcock

    I had thoughts to sell my GS750 to make room for a CBX that a friend of mine decided to sell...well the GS must have knew what was going on because I washed it, and while I had it idling and drying it off I noticed a strange noise from the petcock. Long story short the vacuum diaphragm has started leaking and created a vacuum leak. I confirmed with my wideband o2 that it is leaner at idle with the vacuum line connected.

    So what is the best way to replace the petcock/diaphragm? I have heard of others having trouble with rebuild kits, but have also heard that ebay petcocks seem to be of good quality and last a long time. I don't mind buying an OEM petock, but saving a few dollars never hurts if it doesn't sacrifice quality. On the other hand, mine is still functioning properly it just needs a new diaphragm. Has anyone found a source for just a replacement diaphragm?
  • tom203
    Forum Guru
    Past Site Supporter
    • Aug 2010
    • 8925
    • Norway,Maine

    #2
    Manufacturing methods change over time, so replacement petcock internals tend to be slightly different from 40 year old ones. Best to just get new unit and not have your buyer surprised by leaking gas.
    1981 gs650L

    "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

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    • Gorminrider
      Forum Sage
      Past Site Supporter
      • Aug 2012
      • 4803
      • British Columbia, Canada

      #3
      on ebay, there's georgefix's store. Match your petcock very carefully as there are many differences amongst petcocks.

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      • Guest

        #4
        Originally posted by Gorminrider
        on ebay, there's georgefix's store. Match your petcock very carefully as there are many differences amongst petcocks.
        http://www.ebaystores.com/GEORGEFIXS-MOTORCYCLE-PARTS
        All of the petcocks on his store that are listed for a GS750 have different outlets than mine. When looking directly at the petcock from the left side of the bike both the fuel outlet and vacuum inlet are on the left hand side. Is that factory or is it possible mine has been changed before? Maybe I will just go ahead and order the factory unit from Suzuki.

        Comment

        • GSXR7ED
          Forum LongTimer
          Past Site Supporter
          • Dec 2012
          • 10145
          • DE via L.A.

          #5
          Good call...buying a new OEM petcock.


          Ed
          GS750TZ V&H/4-1, Progressive Shocks, Rebuilt MC/braided line, Tarozzi Stabilizer[Seq#2312]
          GS750TZ Parts Bike [Seq#6036]
          GSX-R750Y (Sold)

          my opinion shouldn't be taken as gospel or in any way that would lead you to believe otherwise (30Sep2021)

          Comment

          • hannibal
            Forum Sage
            • Jun 2015
            • 1033
            • Washington DC

            #6
            Originally posted by The1970's
            All of the petcocks on his store that are listed for a GS750 have different outlets than mine. When looking directly at the petcock from the left side of the bike both the fuel outlet and vacuum inlet are on the left hand side. Is that factory or is it possible mine has been changed before? Maybe I will just go ahead and order the factory unit from Suzuki.
            Pretty sure you have the factory petcock. Mine was oriented that same way.
            Jordan

            1977 Suzuki GS750 (My first bike)
            2000 Kawasaki ZRX1100
            1973 BMW R75/5

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