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GS450 Surreptitious Engine Reassembly

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    #16
    The GS500 crank is a different part number. You'd be taking a risk. I don't know how it's different so I wouldn't know if it matters. Buying a used crank has the benefit of being able to see the crank; buying an engine or bike is assuming that it has a crank that's worth building your engine around.
    '82 GS450T

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      #17
      Good news guys, turns out my shoestring trick worked pretty well. The crank shop I took it to (Marine Crankshaft over in Santa Ana) was very professional and well equipped. Their measurements after micropolishing gave me a 1.3381" and 1.3380" diameter on the rods, well within spec per the Suzuki factory manual. Even surface, and nicely cylindrical.

      $100 got me a magnaflux crack check, precision straightness & measurement of the journal diameters, and micropolishing. Highly recommended.

      Anyway, I received two sets of NOS #2 rod bearings. I'll be plastigaging them tonight.

      Bwringer, the digital micrometer you mentioned only opens to a max of 1", while the journals are >1.3".

      I wound up using the mechanical micrometer set they sell at horror fright as the precision is higher than the digital anyway. If you use them correctly, the manual micrometers are actually pretty spot on, my measurements of the journals varied from the machine shop's by about a tenth of a thou. Just be careful, the hardened carbide tips will scratch/gouge. Doing a measurement of cylindricity involved rotating the crank by 120 degrees and measuring, and measuring for any taper on each journal involved a measurement on two spots for each angle, for each journal. This means a total of 12 measurements, just for the two conrod journals.
      Last edited by free99; 12-15-2020, 03:30 PM.
      1982 GS 450L aka Lil' Red
      1980 GS 1000G aka Big Red (Resto-mod WIP)

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        #18
        Hmm... so I've reassembled the engine, kept everything clean, greased all bearing surfaces, very thin dab of sealant around the perimeter of the case.

        Engine spins freely, seems ok. However, I cannot shift out of a small range of gears. I was careful with the shift forks and such, but I must have made a mistake.

        Would anyone have any suggestions on where to look? I wonder if it has something to do with part number 9.
        1982 GS 450L aka Lil' Red
        1980 GS 1000G aka Big Red (Resto-mod WIP)

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          #19
          Realize that the transmission won't shift smoothly through all the gears without some rotation of the transmission shafts. Are you turning the output shaft some while trying to shift? If not, you might want to try.
          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

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            #20
            Hey Ed, thanks for your advice.

            In this case, even after rotating the tire as best I can within the range permitted by backlash, the gears stay in their limited selection range.
            I'm pretty sure the shift forks are ok/unbent, gear teeth look good. Only thing I can think of is the actual shift mechanism as I had to kind of figure it out from the fiche (part #9).

            Oy vey, and I just filled her up with oil.
            1982 GS 450L aka Lil' Red
            1980 GS 1000G aka Big Red (Resto-mod WIP)

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              #21
              On a whim I loosened the bolt which applies a spring-loaded nub into the shift hub, something clicked. I now can shift into all the gears, except...neutral?

              Gonna fire her up tomorrow morning.
              1982 GS 450L aka Lil' Red
              1980 GS 1000G aka Big Red (Resto-mod WIP)

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                #22
                She fires up, leaking fuel bowl and the other usual annoyances to deal with after cleaning the carbs (I had the engine apart, so why not).

                Bigger issue: shifting is very difficult, it seems I do not have a neutral in spite of the indicator light saying so, and some gears seem to actually fight the engine when I start letting out the clutch. Needless to say, didn't run the engine long.

                (sigh) can someone shed some insight on what's up? I don't want to have to take the engine all the way out but it's starting to look necessary. I never touched the transmission much, may have bumped it while fishing out the crankshaft. What could be wrong?

                Also, I don't know how to confirm that the oil pressure is good to the head.

                I'm glad she runs though.
                1982 GS 450L aka Lil' Red
                1980 GS 1000G aka Big Red (Resto-mod WIP)

                Comment


                  #23
                  What about the shift mechanism behind the clutch? You might want to check that out.
                  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


                    #24
                    Well, everything seemed correct on the gearshift mechanism. I've matched the shift mechanism behind the clutch as best I can to what both suzuki and clymer manuals specify. I verified this last night, that I can grab the arm attached to the shift rod and kind of shift between a couple of gears. But no neutral even though the shift hub is positioned correctly?

                    Something ain't right.
                    1982 GS 450L aka Lil' Red
                    1980 GS 1000G aka Big Red (Resto-mod WIP)

                    Comment


                      #25
                      Phew. Long day yesterday, removed engine, split case, found I'd acctidentally reversed a gear in the transmission, reassembled case, remounted into engine.

                      My back is sore :P

                      Anyway, I'll give her a test tonight or tomorrow once everything else is mounted back up.
                      1982 GS 450L aka Lil' Red
                      1980 GS 1000G aka Big Red (Resto-mod WIP)

                      Comment


                        #26
                        Status update: she's been running pretty well these past few weeks, though seemingly burning a bit of oil. Spark plugs look ok, light dusting of carbon and no wet spots. No blue smoke out the tailpipe, but there is a small amount of blue smoke coming from the exhaust headers. I've washed the bike, and can't determine a source for oil.

                        I'm thinking to work on the top-end now, I bought a bottle-brush hone, new top and base gaskets+o-rings. Perhaps I'll lap the valves as well. Any other suggestions on things to consider working on with this?
                        1982 GS 450L aka Lil' Red
                        1980 GS 1000G aka Big Red (Resto-mod WIP)

                        Comment


                          #27
                          If you're going to do all that, may as well do new piston rings and replace valve seals (since you're taking valves out to lap them anyway). And If I'm not mistaken, a common source of the smoke you see at the headers could be valve seal related.
                          Rich
                          1982 GS 750TZ
                          2015 Triumph Tiger 1200

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

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                            #28
                            Hey Rich, forgot to mention that I got some OEM rings as well. With the hope, of course, that there are no gouges in the cylinder walls..

                            Any recommendations on seals? Leaning towards OEM, though I see some new Viton aftermarket types.
                            Last edited by free99; 02-09-2021, 01:53 PM.
                            1982 GS 450L aka Lil' Red
                            1980 GS 1000G aka Big Red (Resto-mod WIP)

                            Comment


                              #29
                              Sorry, haven't done this work myself yet. Just things I've tossed around in my brain and read about at this point.
                              Rich
                              1982 GS 750TZ
                              2015 Triumph Tiger 1200

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

                              Comment


                                #30
                                Viton valve stem seals are good.
                                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

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