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    hole in my piston

    I somehow manged to burn a hole through my #3 piston on my 78 gs550e...thinking about rebuilding it, but OEM parts are too expensive. So, does anyone out there have a donor motor for cheap, if not, I will be forced to part her out.
    Pretty much everything on it is in good shape except the speedo cover & stator cover.
    Any help would be greatly appreciated.

    #2
    What happened to lean out that cylinder to CAUSE the piston to hole? is what I would like to know! Ray.

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      #3
      Did it look like this?
      1983 GS 1100E w/ 1230 kit, .340 lift Web Cams, Ape heavy duty valve springs, 83 1100 head with 1.5mm oversized SS intake valves, 1150 crank, Vance and Hines 1150 SuperHub, Star Racing high volume oil pump gears, 36mm carebs Dynojet stage 3 jet kit, Posplayr's SSPB, Progressive rear shocks and fork springs, Dyna 2000, Dynatek green coils and Vance & Hines 4-1 exhaust.
      1985 GS1150ES stock with 85 Red E bodywork.

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        #4
        Originally posted by chef1366 View Post
        Did it look like this?
        Hey Bill, that's what nightmares are made of! I don't see a hole through the middle though.
        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

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          #5
          Someone here probably has a used piston

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            #6
            shouldn't I replace the whole set?

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              #7
              detonation is a hole in the middle of the piston

              pre-ignition is damage at the edges of the piston.

              you had a problem for thousands of miles.


              too hot of spark plug. improper ignition timing too low of octane fuel partially plugged pilot jets/lean needle circuit.

              remedy the cause or your next engine will do the same thing.
              SUZUKI , There is no substitute

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                #8
                I gues sthe problem was detonation then, plugs were OEM, always used high octane/premium fuel, had it professionally tuned & carbs professionally cleaned & rebuilt...........maybe I need a new mechanic

                Comment


                  #9
                  Originally posted by SqDancerLynn1 View Post
                  Someone here probably has a used piston

                  Or several for that matter.. Send me a PM, I've got parts from several 550 engines sitting in my garage (LONG Story, search for posts by me to see some of it).

                  Amos

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                    #10
                    Originally posted by dalknob View Post
                    I gues sthe problem was detonation then, plugs were OEM, always used high octane/premium fuel, had it professionally tuned & carbs professionally cleaned & rebuilt...........maybe I need a new mechanic
                    Premium/high octane gasoline will CAUSE detonation in relatively low CR motors. You should be using 87. Period. Don't believe me? Do some research. High octane fuel will preignite/detonate in a stock GS motor. You never noticed it pinging?

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                      #11
                      I believe you now!

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                        #12
                        Carbon in the combustion chamber or too hot of a plug may have caused this pre-ignition problem.

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                          #13
                          Rebuilding the top end with used, but good, parts is fine but you need to figure out what caused the detonation or the same thing will happen to the new engine.

                          Was the bike stock or did you change the intake and/or exhaust system? Was the bike running well before this happened? A lean mixture will cause the engine to run hot, such as if the intake boot O-rings were leaking, and a lean mixture can cause detonation. I've never heard about Cafe's claim that high octane fuel will cause detonation, and I seriously doubt that was the cause.
                          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


                            #14
                            Originally posted by TheCafeKid View Post
                            Premium/high octane gasoline will CAUSE detonation in relatively low CR motors. You should be using 87. Period. Don't believe me? Do some research. High octane fuel will preignite/detonate in a stock GS motor. You never noticed it pinging?
                            How's that? I thought the flame front propagation was slower with higher octane, resulting in less chance of preignition/detonation. I found this with a quick Google search:



                            6.16 What happens if I use the wrong octane fuel?

                            If you use a fuel with an octane rating below the requirement of the engine,
                            the management system may move the engine settings into an area of less
                            efficient combustion, resulting in reduced power and reduced fuel economy.
                            You will be losing both money and driveability. If you use a fuel with an
                            octane rating higher than what the engine can use, you are just wasting
                            money by paying for octane that you can not utilise. The additive packages
                            are matched to the engines using the fuel, for example intake valve deposit
                            control additive concentrations may be increased in the premium octane grade.
                            If your vehicle does not have a knock sensor, then using a fuel with an
                            octane rating significantly below the octane requirement of the engine means
                            that the little men with hammers will gleefully pummel your engine to pieces.

                            Comment


                              #15
                              Higher octane causing pre-ignition or detonation is a new one on me too. If anything it would lessen the chances. This guy's problem was caused by more than octane rating.

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