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    Base gaskets are critical. OEM only, in my opinion.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

    Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

    Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

    KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

    Comment


      Well, the second gasket was cancelled and refunded by the seller, claiming “we couldn’t find it”. So I just bought this one. Hope this one works out. 3rd time’s a charm, right? It is OEM NOS.

      Rich
      1982 GS 750TZ
      2015 Triumph Tiger 1200

      BikeCliff's / Charging System Sorted / Posting Pics
      Destroy-Rebuild 750T/ Destroy-Rebuild part deux

      Comment


        The other thing to be aware of, is the o-rings on the bottom of the cylinder liners. If originals, they most certainly will be hard and brittle.

        The liners are fixed at the head mating surface by a step on the outer upper edge of the liner and a corresponding rebate in the alloy clamped down by the cylinder head. At the bottom the liners 'float' in the alloy finned barrels. This is to accommodate the different coefficients of expansion between the iron liners and alloy barrels as the engine heats up and cools down. The o-rings sit in grooves in the bottom of the barrels to seal the the liners to the barrels but allow them to slide under expansion and contraction ensuring the liners don't distort. The o'rings are to stop oil getting between the liners and the fins.

        I've heard different explanations of why this might be a problem.

        Some say the oil can make its way to the head gasket and leak out the joint, other's that the alloy in the fins is porous and can also leak/sweat oil though to the outside of the fins. Some say it can interfere with heat transfer from the liner to the fins, but I find that unlikely (think oil-cooling). Some air-cooled engines don't have them, but Suzuki put them there. So I'm banking there's a reason why.
        sigpicDarryl from Kiwiland

        1982 GSX1100S Katana
        1982 GSX750S Katana
        1982 GS650G Katana

        Comment


          Originally posted by KiwiAlfa156 View Post
          The other thing to be aware of, is the o-rings on the bottom of the cylinder liners. If originals, they most certainly will be hard and brittle.

          The liners are fixed at the head mating surface by a step on the outer upper edge of the liner and a corresponding rebate in the alloy clamped down by the cylinder head. At the bottom the liners 'float' in the alloy finned barrels. This is to accommodate the different coefficients of expansion between the iron liners and alloy barrels as the engine heats up and cools down. The o-rings sit in grooves in the bottom of the barrels to seal the the liners to the barrels but allow them to slide under expansion and contraction ensuring the liners don't distort. The o'rings are to stop oil getting between the liners and the fins.

          I've heard different explanations of why this might be a problem.

          Some say the oil can make its way to the head gasket and leak out the joint, other's that the alloy in the fins is porous and can also leak/sweat oil though to the outside of the fins. Some say it can interfere with heat transfer from the liner to the fins, but I find that unlikely (think oil-cooling). Some air-cooled engines don't have them, but Suzuki put them there. So I'm banking there's a reason why.
          Darryl, thanks for the thought, and the explanation of why those are there. I appreciate any reminders. Yes, I’ve already removed those big orings that live in the channel around the base of each cylinder. They’re on order along with the other wear items: gaskets, copper washers, orings that fit around some head bolts, piston rings, cam chain tensioner gasket, tack drive orings, etc. All those things were new 11,000 miles ago when I rebuilt this top end. At that time I did not lap valves and replace piston rings. This time, I am.
          Last edited by Rich82GS750TZ; 11-27-2023, 08:54 PM.
          Rich
          1982 GS 750TZ
          2015 Triumph Tiger 1200

          BikeCliff's / Charging System Sorted / Posting Pics
          Destroy-Rebuild 750T/ Destroy-Rebuild part deux

          Comment


            Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
            Yeah, I forgot the dowels.
            2002 bmw r1150gs 1978 gs1000E skunk les pew 1979 gs1000L dragbike
            82 gs1100L probably the next project
            1980 gs1000G the ugly 1978 gs750E need any parts?
            https://m.youtube.com/watch?v=m_m2oYJkx1A
            1978 gs1000E skunk #2 RLAP

            Comment


              Originally posted by Rich82GS750TZ View Post

              Darryl, thanks for the thought, and the explanation of why those are there. I appreciate any reminders. Yes, I’ve already removed those big orings that live in the channel around the base of each cylinder. They’re on order along with the other wear items: gaskets, copper washers, orings that fit around some head bolts, piston rings, cam chain tensioner gasket, tack drive orings, etc. All those things were new 11,000 miles ago when I rebuilt this top end. At that time I did not lap valves and replace piston rings. This time, I am.
              Rich, it sounds like you've got it well in hand. Good work, my friend. I'm enjoying the thread.
              sigpicDarryl from Kiwiland

              1982 GSX1100S Katana
              1982 GSX750S Katana
              1982 GS650G Katana

              Comment


                Originally posted by Eli69 View Post
                Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
                Yeah, I forgot the dowels.
                Yep, remembered those too. Any damaged dowels (had a few) noted during disassembly have been ordered. Big ones between base/barrels, barrels/head, head/valve cover, and a couple of the little ones on a cam cap or two.
                Rich
                1982 GS 750TZ
                2015 Triumph Tiger 1200

                BikeCliff's / Charging System Sorted / Posting Pics
                Destroy-Rebuild 750T/ Destroy-Rebuild part deux

                Comment


                  Most parts arrived today. Waiting on the base gasket yet. I will gap and install new rings, hone the cylinders, then I can start the rebuild. Hope to get a lot done this weekend.

                  Last edited by Rich82GS750TZ; 12-01-2023, 11:22 AM.
                  Rich
                  1982 GS 750TZ
                  2015 Triumph Tiger 1200

                  BikeCliff's / Charging System Sorted / Posting Pics
                  Destroy-Rebuild 750T/ Destroy-Rebuild part deux

                  Comment


                    Originally posted by Eli69 View Post
                    Don't forget the dowels. Seems like a thing you wouldn't forget doesn't it? You would think that......
                    Yeah, I forgot the dowels.
                    I got you beat.
                    I was assembling the valves in a cylinder head.
                    I was almost done when I looked to see the valve stem seals still in the package sitting on the bench.
                    My Motorcycles:
                    22 Kawasaki Z900 RS (Candy Tone Blue)
                    22 BMW K1600GT (Probably been to a town near you)
                    82 1100e Drag Bike (needs race engine)
                    81 1100e Street Bike (with race engine)
                    79 1000e (all original)
                    82 850g (all original)
                    80 KZ 650F (needs restored)

                    Comment


                      Have the day off and hoping to get the new rings on. Replacing rings just because I’m in there anyway, and 38,000 miles. But new rings orientation has me a bit confused and I want to make sure I get this right.

                      Manual has me looking for a noticeable taper on the second ring:


                      original rings, no appreciable taper that I can see:


                      New rings profiles look identical to me. Tops are marked. One is definitely silver/shiny, the other dulll/black. I’m about 73% certain the shiny one goes on top, from the note in the manual about the top ring being chrome plated.






                      no issues with the oil rings, those are straightforward.

                      edit to add- the video below set me straight. The silver in the top/compression ring. The black is the second/scraper ring.

                      Last edited by Rich82GS750TZ; 12-01-2023, 01:00 PM.
                      Rich
                      1982 GS 750TZ
                      2015 Triumph Tiger 1200

                      BikeCliff's / Charging System Sorted / Posting Pics
                      Destroy-Rebuild 750T/ Destroy-Rebuild part deux

                      Comment


                        Made good progress today. Was just about to pop in a new oil filter and fresh oil. When I was tightening the drain bolt, thought I felt the crush washer crush, then gave the wrench a little more. What I actually felt was the pan threads giving way. FML. Well, at least I have a spare oil pan that was already cleaned up and ready to go. Have a pan gasket on the shelf too. Spent the last hour or so scraping the old gasket. Decided to call it quits for the night and enjoy a beer. I could finish it up tomorrow, we’ll see how it goes.

                        I know there’s a new member here with the same bike who just did the same thing. Can’t seem to find a torque spec for the oil drain bolt in any of my references. Never had this happen before. Think I was getting tired and my built-in ugga-dugga meter was out of calibration.

                        Rich
                        1982 GS 750TZ
                        2015 Triumph Tiger 1200

                        BikeCliff's / Charging System Sorted / Posting Pics
                        Destroy-Rebuild 750T/ Destroy-Rebuild part deux

                        Comment


                          The drain bolt threads on my 850 also stripped out.

                          Other members here reported using a special oversize bolt that cut it's own threads in the oil pan. Brian (bwringer) very kindly sourced one and posted it to me together with a few tubes of Honda moly paste for the drive splines.

                          That fix worked well and has been leak-free for some years.
                          1981 GS850G "Blue Magic" (Bike Of The Month April 2009)

                          1981 GS1000G "Leo" (Bike Of The Month August 2023)

                          Comment


                            Originally posted by 2BRacing View Post
                            The drain bolt threads on my 850 also stripped out.

                            Other members here reported using a special oversize bolt that cut it's own threads in the oil pan. Brian (bwringer) very kindly sourced one and posted it to me together with a few tubes of Honda moly paste for the drive splines.

                            That fix worked well and has been leak-free for some years.
                            If you or bwringer knows exactly what that is I’ll buy one to fix this damaged pan, just to have as a spare. I had thought of doing some kind of repair in situ, but figured I’d have to take the pan off anyhow. Wouldn’t want thread cuttings left in there.
                            Last edited by Rich82GS750TZ; 12-02-2023, 12:00 PM.
                            Rich
                            1982 GS 750TZ
                            2015 Triumph Tiger 1200

                            BikeCliff's / Charging System Sorted / Posting Pics
                            Destroy-Rebuild 750T/ Destroy-Rebuild part deux

                            Comment


                              "It's always somethin !"
                              2002 bmw r1150gs 1978 gs1000E skunk les pew 1979 gs1000L dragbike
                              82 gs1100L probably the next project
                              1980 gs1000G the ugly 1978 gs750E need any parts?
                              https://m.youtube.com/watch?v=m_m2oYJkx1A
                              1978 gs1000E skunk #2 RLAP

                              Comment


                                Originally posted by Rich82GS750TZ View Post

                                If you or bwringer knows exactly what that is I’ll buy one to fix this damaged pan, just to have as a spare. I had thought of doing some kind of repair in situ, but figured I’d have to take the pan off anyhow. Wouldn’t want thread cuttings left in there.
                                It was a "+1 oversize" sump bolt in the standard 14 x 1.25 pitch. They are available in auto parts stores. Unfortunately I cannot locate my notes on that item now - apologies for not being able to provide you with better info.

                                I put grease on the bolt and turned it slowly in-and-out bit-by-bit until it was all the way in, and then removed it to clean the cuttings caught in the grease.​
                                1981 GS850G "Blue Magic" (Bike Of The Month April 2009)

                                1981 GS1000G "Leo" (Bike Of The Month August 2023)

                                Comment

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