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    Snapped Exhaust Port Thread.

    Good afternoon,
    Firstly, apologies for my layman's terms…I'm new to this.

    Bought somebody else's half finished project, which I will learn from. (Never do this, is the lesson!)

    Was attaching the exhaust today and on one of the ports, the actually wall of the head (where the bolt goes in) has snapped off all the way back.

    Now I have googled this and all I can get is 'broken exhaust stud' or 'bolt needs drilling out.' This isn't the problem.

    Are there any ways around this, or do I have to try and find a full new head for it? (Bike is an '85 GS650GT)

    All other bolts go in fine and everything else is now working as it should.

    Its so frustrating!

    Help please!

    #2
    What do you mean by "all the way back"????? Is it way down the hole and there are lots of threads near the face of the head where the stud goes in?? If its broke off deep in the hole and there are sufficient threads to get a bolt in, then I would just use a CHASE....not a cutting tap..and clean the threads..then just use a shorter bolt that will allow you to fit up the pipe. Leave the broke piece in as it is of no consequence at that point.

    Give a more in depth summary of what there is to deal with please.
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

    Comment


      #3






      Hi Chuck,

      Thanks for the reply. Ive just nipped out and taken a picture to try and better describe.

      The first picture is how it should look.

      The second picture shows how all of the metal (which contains the thread for the bolt to go into) has been snapped off at some point.

      So there is nowhere for the bolt to go?

      Hope this explains better...

      Comment


        #4
        Looks like you can get that fixed pretty easily, but you will probably be better off removing the head to take it into a shop.

        Call around and find someone who can weld aluminum and they could advise you if you need to disassemble the engine or not.

        Best way would be for them to build the area up and then drill and tap to accept a new bolt.

        Good luck.
        2018 Honda Africa Twin AS
        2013 DR 650 Grey, sold 1981 GS 650E Silver,

        1980 GS1000ST Blue & White, X2

        2012 DL650 Vstrom Foxy Orange, in storage
        1981 CT110 X2 "Postie Bikes" Gone to a New Home.
        2002 BMW 1150 GS Blue & White - Sold
        1975 BMW R90/6 Black - Sold 1984 GS1150EF Sold
        1982 BMW R100 Africa trip, Stolen - Recovered- Sold
        1977-1980 Suzuki GS550, GS1000E, GS1000S GSX750, GSX1100,s
        Hondas ST90, CR125 CB175 , CB350 CB750, NSU Quickly, Yamaha RD's 350/400,

        Comment


          #5
          ( To ME ) it looks like they have just knackered up the outer rim badly. Take a wire and stick in the hole to see if you can get at a minimum of say 10MM of depth or more..the original holes are around 40MM deep and the bolts are around 35MM from shoulder to tip.

          So, if you have sufficient depth, you can just use a Dremel or similar to smooth off the face to get to some decent threads again, then run the chase, and work a bolt in. Once youve established the bolt goes in, use one that will allow you to seat it with some space at the bottom. You DO NOT want to use too long a bolt. There are oil gallies in the head and you dont want the bolt to opunch thru the head...bad bad JU JU follows!!!
          MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
          1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

          NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


          I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

          Comment


            #6
            Ah, this is what I was thinking. Really gutted as it has taken me so long to get to this stage.

            Really appreciate the reply, thanks Kiwi.

            Comment


              #7
              Haha thanks Chuck, I'll give that a go first. Cheers guys.

              Comment


                #8
                Here's a product that may work, never used it but worth looking at.

                2018 Honda Africa Twin AS
                2013 DR 650 Grey, sold 1981 GS 650E Silver,

                1980 GS1000ST Blue & White, X2

                2012 DL650 Vstrom Foxy Orange, in storage
                1981 CT110 X2 "Postie Bikes" Gone to a New Home.
                2002 BMW 1150 GS Blue & White - Sold
                1975 BMW R90/6 Black - Sold 1984 GS1150EF Sold
                1982 BMW R100 Africa trip, Stolen - Recovered- Sold
                1977-1980 Suzuki GS550, GS1000E, GS1000S GSX750, GSX1100,s
                Hondas ST90, CR125 CB175 , CB350 CB750, NSU Quickly, Yamaha RD's 350/400,

                Comment


                  #9
                  Another thought.....Youre gonna be removing material off the one side which will most likely make the flange set cocked to that side. I would place a washer between the flange and the head there so that when you tighten the bolts they draw the flange up and keep it as level from side to side as is reasonably possible. This will keep excess side forced stress off the header bolts.
                  MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                  1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                  NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                  I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                  Comment


                    #10
                    If I'm understanding this right, you stripped the threads in the head without any of the stud remaining in the head, same as I did,in which case I used a longer stud 60 mm overall if I remember correctly and there was sufficient depth and thread to accommodate this stud without any engineering work. This was an 82 1100 so I don't know if your head will accept same studs. Hope this helps.

                    Comment


                      #11
                      As I understand it, the previous owner has beat it up. I would run a wire down the hole and find the REAL depth without any assumptions. Make a wrong "guess" and youre done.
                      MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
                      1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

                      NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


                      I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

                      Comment


                        #12
                        I'd go with a stud instead of a bolt. In fact I'd go studs on all the exhaust bolt holes. Use a bottoming tap to thread it back. If the current threads are too wallowed out then go with a Helicoil and be done with it.

                        1980 GS1000GT (Daily rider with a 1983 1100G engine)
                        1998 Honda ST1100 (Daily long distance rider)
                        1982 GS850GLZ (Daily rider when the weather is crap)

                        Darn, with so many daily riders it's hard to decide which one to jump on next.

                        JTGS850GL aka Julius

                        GS Resource Greetings

                        Comment


                          #13
                          As previously mentioned,

                          Make no assumptions as to the depth of the hole/threads, they may be different

                          and

                          I'd go with stud's on all the exhaust bolt holes.

                          Comment

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