Announcement

Collapse
No announcement yet.

750 Katana Resurrection

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Had a good look at the ports and found various flaws and steps and undercuts where the inlet port joins the valve seat. Which is the most important part of the port - the throat.



    Basically the turbulence created by the casting flaws at this point has is extremely detrimental to flow past the valve.


    I will carefully cut back imperfection and blend this section of the port back into the bowl. What is important is to maintain the valve to throat percentage which I measured at 82% stock. The throat acts like a venturi so I don't want to disturb this area at all. Work on the port above the throat has to be carefully done but isn't as critical.



    I've started on one of the less problematic ports.




    sigpicDarryl from Kiwiland

    1982 GSX1100S Katana
    1982 GSX750S Katana
    1982 GS650G Katana

    Comment


      Did some work on the worst of the inlets


      Comparison.



      A mark is still visible, but it feels smooth and a dentists pick doesn't catch in it.


      sigpicDarryl from Kiwiland

      1982 GSX1100S Katana
      1982 GSX750S Katana
      1982 GS650G Katana

      Comment


        this build thread is a real education in itself, thanks for sharing your work in such detail--you say it's therapy, well, I thank you for sharing your time on the professor's couch.

        I could never quantify the time I have spent fishing, either... probably best not to think about it too hard.
        1978 GS 750 E
        1979 XS11 Standard
        1973 CB450

        Comment


          Thanks Forden, that's very flattering. Just sharing the journey and posting what I think is interesting. Hopefully others, such a yourself, find it interesting too.
          sigpicDarryl from Kiwiland

          1982 GSX1100S Katana
          1982 GSX750S Katana
          1982 GS650G Katana

          Comment


            Pretty much finished the inlet ports. Got some valves coming to replace some that need to be swapped out.


            Tried to take minimal material out as I'd like to maintain as much port velocity as possible. Also left the throat area as undisturbed as possible apart from cutting out the casting flaws on the long side and blending a gentle radius back into the bowl. On the short side I radiused it as best as possible, removing the sharp step which is ringed in red below. Again removing minimal metal.



            Cleaned up the casting core flashings in the turn of the ports and blended then into the throat area. The bottom pic above is one done, and one to be done. Surface finished in 80 grit.



            Fitted new roller bearing on the clutch release shaft. Never regretted buying a hydraulic press..


            sigpicDarryl from Kiwiland

            1982 GSX1100S Katana
            1982 GSX750S Katana
            1982 GS650G Katana

            Comment


              Exhaust ports cleaned up. A couple of the inlet valves are badly cupped on the sealing face. It looks like the valves have been heavily lapped on using an electric drill. Replacements on the way. A serviceable inlet is shown for comparison.



              I'm using a marker pen as a substitute for engineers blue to reveal and measure the seat contact width. The inlets appear to be over the 1.1mm limit. As do the exhausts.
              sigpicDarryl from Kiwiland

              1982 GSX1100S Katana
              1982 GSX750S Katana
              1982 GS650G Katana

              Comment


                Ugh: These days someone has always been there before you.
                1986 1150EF
                2008 GS1250SEA

                Comment


                  Originally posted by Big Block View Post
                  Ugh: These days someone has always been there before you.
                  Ain't that the truth
                  sigpicDarryl from Kiwiland

                  1982 GSX1100S Katana
                  1982 GSX750S Katana
                  1982 GS650G Katana

                  Comment


                    Got a spare 17" Eneki rear for the 750. It's marked "MT" which as far as I know is 'motorcycle tubeless' Of course being early 80s and not being specifically marked as tubeless it has the right rim profile but won't take a tubeless valve stem.



                    Counterbored a face for the valve stem seal. And used the metal valve stem face with some grinding paste to remove the cutter chatter marks.
                    sigpicDarryl from Kiwiland

                    1982 GSX1100S Katana
                    1982 GSX750S Katana
                    1982 GS650G Katana

                    Comment




                      Cases split. The rotor/fly wheel wasn't coming off with heat and some pretty heavy slams with a slide hammer. As there's no oil seal or anything to replace, I'll just leave it in place.

                      So clean, measure, paint and reassemble.
                      sigpicDarryl from Kiwiland

                      1982 GSX1100S Katana
                      1982 GSX750S Katana
                      1982 GS650G Katana

                      Comment


                        Looks good. I was there a few weeks ago installing a new output shaft.
                        1986 1150EF
                        2008 GS1250SEA

                        Comment


                          Originally posted by Big Block View Post
                          Looks good. I was there a few weeks ago installing a new output shaft.
                          Yeah, it is looking good, Crank journals look pristine and lightest of wear marks on the shell bearings. Gear teeth show next to no wear, selector forks ditto. Looks like the cases have never been split. Given the ham-fisted work on the top-end, I needed to have a look to quell any doubts and I'm really pleased at the condition of the bottom-end and gearbox. I'll check all the bearings, give everything a clean and paint the cases, and start the reassembly. What was the issue with your output shaft BB?
                          sigpicDarryl from Kiwiland

                          1982 GSX1100S Katana
                          1982 GSX750S Katana
                          1982 GS650G Katana

                          Comment


                            Previous owner let the front sprocket get loose and chewed up the splines I figure. It's a good thing I pulled it down too, the clutch hub was worn and cracked. Everything else was like new though. Really enjoying this thread, very nice workmanship.
                            1986 1150EF
                            2008 GS1250SEA

                            Comment


                              Some progress while recovering from Covid. The inside of the engine was pretty dirty with firm sludge remaining where the particulates have settled out of the oil as it sat cold for the last 10+ years.




                              So I spent a couple of days cleaning the cases inside and removing lose paint, oxide and residual dirt.





                              Reassembled the empty cases, masked up, grease and wax remover, primer grey and the semi-gloss black engine enamel.




                              sigpicDarryl from Kiwiland

                              1982 GSX1100S Katana
                              1982 GSX750S Katana
                              1982 GS650G Katana

                              Comment


                                Will start loading the cases shortly



                                sigpicDarryl from Kiwiland

                                1982 GSX1100S Katana
                                1982 GSX750S Katana
                                1982 GS650G Katana

                                Comment

                                Working...
                                X