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    #1

    piston fun :(






    SO it appears the wrist pin on the #1 piston has been hammering the circle clip. There is about 1mm of movement side to side on the wrist pin. and it looks like the circle clip has been driven deeper into the groove.

    none of the other pistons have cracked around the clip but there appears to be some good movement there and some hammering on the clips as well.

    SHould i be looking for 4 good used pistons? it's the damn 1000cc 16v motor so all pistons are discontinued. I am guessing the 1100 pistons are a bigger diameter then these which are 69mm w/ 18mm wrist pins.

    the cylinder walls seem good so where ever that piece of piston is it didn't score the wall when it left.
    78 GS1000 Yosh replica racer project
    82 Kat 1000 Project
    05 CRF450x
    10 990 ADV-R The big dirt bike

    P.S I don't check PM to often, email me if you need me.
    Tags: None
    #2
    That's basically the 16 valve 750 pistons. I don't know if you'll have unintended consequences (such as the piston being too long and blowing the motor), but the GS750 kits from wiseco come in at 70mm w/ 18mm wrist pins.
    Yamaha fz1 2007

    Comment

      #3
      Glad to see the piston fragment didn't score the bore, very luckly! Now I understand the request for the pistons, read the other post first, cheers.
      Badgezz, we don need noh stinkin' badgezz!
      Shin-Ken 1074
      1982 GSX1100SXZ Wire Wheel Katana - BOM Nov 2011
      1981 GSX1135 Katana Build completed Mar 2024, Curb Weight, all fluids and 21 lt fuel = 206 kg.

      Comment

        #4
        Originally posted by first timer View Post





        SO it appears the wrist pin on the #1 piston has been hammering the circle clip. There is about 1mm of movement side to side on the wrist pin. and it looks like the circle clip has been driven deeper into the groove.

        none of the other pistons have cracked around the clip but there appears to be some good movement there and some hammering on the clips as well.

        SHould i be looking for 4 good used pistons? it's the damn 1000cc 16v motor so all pistons are discontinued. I am guessing the 1100 pistons are a bigger diameter then these which are 69mm w/ 18mm wrist pins.

        the cylinder walls seem good so where ever that piece of piston is it didn't score the wall when it left.
        That piston is a mess. Looks like that pin is further than 1 mm from what's left of the circlip. Is the circlip removed from the other end? If not, you need to investigate why there has been so much free play between the clips and the wrist pin. I suspect that someone has mis-matched the wrist pins and the circlips.

        I would look for some new replacement OS pistons. If you don't want to bore, good luck with the search for replacement second hand pistons!
        :) The road to hell is paved with good intentions......................................

        GS 850GN JE 894 10.5-1 pistons, Barnett Clutch, C-W 4-1, B-B MPD Ignition, Progressive suspension, Sport Demons. Sold
        GS 850GT JE 1023 11-1 pistons. Sold
        GS1150ES3 stock, V&H 4-1. Sold
        GS1100GD, future resto project. Sold

        http://i155.photobucket.com/albums/s...s/P1000001.jpg
        http://i155.photobucket.com/albums/s...s/P1000581.jpg

        Comment

          #5
          I typed in GS1000 piston on ebay and it looks like there are some being sold individually and then there are wiseco kits being sold as well....but I don't know if I am looking for the right pistons.

          Comment

            #6
            No part numbers for te wiseco's to refer to?

            Comment

              #7
              I bet money it was broken before installed into the bore.

              By the way the piston pin circlip opening HAS to be at 12 o clock or 6 o clock.otherwise they will pop out. that does make a mess of the cylinder.

              just a tip for those who do not know.
              SUZUKI , There is no substitute

              Comment

                #8
                no wiseco pistons, unless i want to go to a 1166 bore, I am sure there are plenty 1000 8v pistons but not so many 16v 1000 pistons.... I'll double check.

                Talked to Ray, he suggest just using a 1100 block and pistons for now until i can find some 1000 pistons or get a set custom made. I rather not bore the cylinder because I would like to keep the bike stock, the 1000cc 16v is what makes it unique.

                I'll pull the wrist pin and measure it today and see whats up. I am sure the motor has been apart before since the crank has been welded plus the original owner told me they welded it.

                There is an intresting idea, anyone know if a 16v 750 wiseco kit would work with the Kat? What makes the 750 and the 1000 differant? the stroke?

                What is the typical side to side tolerance for wrist pin movement?

                I'll pull the pistons and take some more photos.

                thanks Guys,
                Ryan
                78 GS1000 Yosh replica racer project
                82 Kat 1000 Project
                05 CRF450x
                10 990 ADV-R The big dirt bike

                P.S I don't check PM to often, email me if you need me.

                Comment

                  #9
                  Originally posted by trippivot View Post
                  I bet money it was broken before installed into the bore.

                  By the way the piston pin circlip opening HAS to be at 12 o clock or 6 o clock.otherwise they will pop out. that does make a mess of the cylinder.

                  just a tip for those who do not know.
                  why? a circlip in a groove, installed correctly will not pop out just because its not facing the right way. where did this information come from? i have been building bike engines for over 20 years now and have never worried about where the circlip sits and have had no failures yet!
                  1978 GS1085.

                  Just remember, an opinion without 3.14 is just an onion!

                  Comment

                    #10
                    Never seen any specs for wrist pin to circlip end clearance. I would expect it to be in the 0.006" - 0.010" range. Any closer than that and you would be struggling to fit the second circlip in the groove.
                    :) The road to hell is paved with good intentions......................................

                    GS 850GN JE 894 10.5-1 pistons, Barnett Clutch, C-W 4-1, B-B MPD Ignition, Progressive suspension, Sport Demons. Sold
                    GS 850GT JE 1023 11-1 pistons. Sold
                    GS1150ES3 stock, V&H 4-1. Sold
                    GS1100GD, future resto project. Sold

                    http://i155.photobucket.com/albums/s...s/P1000001.jpg
                    http://i155.photobucket.com/albums/s...s/P1000581.jpg

                    Comment

                      #11
                      Originally posted by Agemax View Post
                      why? a circlip in a groove, installed correctly will not pop out just because its not facing the right way. where did this information come from? i have been building bike engines for over 20 years now and have never worried about where the circlip sits and have had no failures yet!
                      That's a good question - I was told when I was a lad about spinning the clip in to the right position and was too young to ask why. I've always made sure the clip is in the 'right' position but you've got me wondering now.
                      79 GS1000S
                      79 GS1000S (another one)
                      80 GSX750
                      80 GS550
                      80 CB650 cafe racer
                      75 PC50 - the one with OHV and pedals...
                      75 TS100 - being ridden (suicidally) by my father

                      Comment

                        #12
                        THe clips probably walk a bit. I found clips at different positions, some in the "wrong" place, when I took a 550 apart last year. I suspect this failure was metal fatigue pushed by detonation but who knows for sure. Could just as easily been a bad piston or flawed casting.
                        1981 GS650G , all the bike you need
                        1980 GS1000G Power corrupts, and absolute power corrupts absolutely

                        Comment

                          #13
                          I pull my pistons and took some pics, seems like most of them are in good shape, # 4 might have a little bit of wear around the circle clips but nothing major.

                          See the link below, i put them in a group and labeled each photo related to piston number. Please comment. The last two pictures in the group are one of my pistons (the extra carbony one, which has a bigger spark top) and the ones Katana_man (OSS) has offered me (the ones with the smaller spark top) Does the size of the spark top matter? As long as both pistons have a dia of 69.400 - 69.415mm?

                          katana pistons
                          http://www.flickr.com/photos/monknuts/sets/72157614913506095/
                          Explore this photo album by monknuts on Flickr!


                          I also measured the side to side clearance of the rods as shown in the book, they all seem in spec #1 = .533mm (the bad clip piston) #2 = .508mm #3 = .406mm #4 = .432mm. The standard range in the book is .10 - .65mm with a service limit of 1mm. So they seem ok. I also tried measuring the small ends with my digital calipers and they all seem to be just under 18mm, I needed to hunt up a bore gauge to be more accurate.
                          78 GS1000 Yosh replica racer project
                          82 Kat 1000 Project
                          05 CRF450x
                          10 990 ADV-R The big dirt bike

                          P.S I don't check PM to often, email me if you need me.

                          Comment

                            #14
                            Can't see anything that would suggest the pistons are bad, except for the broken one of course.

                            I don't understand why that one piston (labeled "piston") seems to have the extra raised area in the middle while the other pistons don't have it. The group photo (labled "piston 2") don't show the piston with the raised area either. Is that an extra piston or what?
                            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

                              #15
                              piston 1 are the type of pistons in my bike currently, piston 2 is a set of possable replacement pistons.
                              78 GS1000 Yosh replica racer project
                              82 Kat 1000 Project
                              05 CRF450x
                              10 990 ADV-R The big dirt bike

                              P.S I don't check PM to often, email me if you need me.

                              Comment

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