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Swapping 1980 850 engine into 1979 gs 850

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    Swapping 1980 850 engine into 1979 gs 850

    Hey y’all

    I’ve got a 1979 gs850 that I’m doing a full rebuild on. I’m having to swap out the engine with one from a later mode due to the fact that when I drained the oil it was holding about 2+ liters of water in the crankcase. My question is, what options would I have for carburetors since I’m sure mine won’t fit on the newer engine. It appears the newer style CV carbs are harder to come by on eBay. Are there other models that had the same carbs just with different jetting. Any aftermarket options that may be worth a look? Thanks in advance

    #2
    Just tear down the top ends of both motors and swap the 79 head onto the newer engine
    Problem solved. carbs, boots and air box stay the same
    1978 GS 1000 (since new)
    1979 GS 1000 (The Fridge, superbike replica project)
    1978 GS 1000 (parts)
    1981 GS 850 (anyone want a project?)
    1981 GPZ 550 (backroad screamer)
    1970 450 Mk IIID (THUMP!)
    2007 DRz 400S
    1999 ATK 490ES
    1994 DR 350SES

    Comment


      #3
      Yep, that would be the easiest, even though you would need to get a head gasket and a base gasket.

      Carbs are not that hard to get. Although there are subtle differences besides jetting, everything from a 550 though 850 had BS32SS carbs.

      .
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      mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
      hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
      #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
      #2 son: 1980 GS1000G
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      Comment


        #4
        Originally posted by Big T View Post
        Just tear down the top ends of both motors and swap the 79 head onto the newer engine
        Problem solved. carbs, boots and air box stay the same
        Honestly a little upset I didn’t think of that as a possibility, thanks for the advice. Think that’ll definitely be the easiest option

        Comment


          #5
          Originally posted by Steve View Post
          Yep, that would be the easiest, even though you would need to get a head gasket and a base gasket.

          Carbs are not that hard to get. Although there are subtle differences besides jetting, everything from a 550 though 850 had BS32SS carbs.

          .
          good to know I’ve got options. I’ll keep an eye out for any options. If all else fails I’ll go to the head swap like Big T suggested and use my own carbs. Thanks again for the help. Definitely glad I joined this forum, I can tell I’m gonna get a lot of useful info here

          Comment


            #6
            You'll have to obtain the drive shaft from the 80 bike too. The flanges on the back of the engines are different, unless you want to simply swap the flange from the 79 to the 80 engine, but that's best left undisturbed if you can.
            ---- Dave
            79 GS850N - Might be a trike soon.
            80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
            79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
            92 XJ900F - Fairly Stock, for now.

            Only a dog knows why a motorcyclist sticks his head out of a car window

            Comment


              #7
              Originally posted by Grimly View Post
              You'll have to obtain the drive shaft from the 80 bike too. The flanges on the back of the engines are different, unless you want to simply swap the flange from the 79 to the 80 engine, but that's best left undisturbed if you can.
              noted, didn’t even realize they were different. We’re they all the same after a certain year or specific years I should look for

              Comment


                #8
                As Steve noted, pull the cylinder block when you change the head. It's often that you disturb the base gasket when pulling the head and oil leaks occur. So, spend the $$ on the base gasket and the oval O rings.

                Also, a good time to replace the valve stem seals and end half moons.
                1978 GS 1000 (since new)
                1979 GS 1000 (The Fridge, superbike replica project)
                1978 GS 1000 (parts)
                1981 GS 850 (anyone want a project?)
                1981 GPZ 550 (backroad screamer)
                1970 450 Mk IIID (THUMP!)
                2007 DRz 400S
                1999 ATK 490ES
                1994 DR 350SES

                Comment


                  #9
                  They changed in 1980. It caught me out the first time I swapped an engine into my 79. The shaft is otherwise identical, so fits the pumpkin end fine, I think Zuk may have beefed up the flexy joint slightly and to accomodate that, the flange was different.
                  Even though I suggested that simply swapping the flange might be sufficient, I can't be sure the splines on the inside of the flanges are the same, so best to just swap the driveshafts over.
                  ---- Dave
                  79 GS850N - Might be a trike soon.
                  80 GS850T Single HIF38 S.U. SH775, Tow bar, Pantera II. Gnarly workhorse & daily driver.
                  79 XS650SE - Pragmatic Ratter - goes better than a manky old twin should.
                  92 XJ900F - Fairly Stock, for now.

                  Only a dog knows why a motorcyclist sticks his head out of a car window

                  Comment

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