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Sudden massive top end mangling

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    #1

    Sudden massive top end mangling

    Here's the history of the bike to my knowledge:

    82 GS 750 with 16v head. 27,000 miles. Runs great, no smoke. I've run Amsoil synthetic since I got it with 24,000.

    I adjusted the valves 1,500 miles ago or so and found them all too tight, so I loosened them. After that, one made some noise but I didn't mind.

    I just took the longest trip I've ever done on the bike, about 100 miles each way to see my girlfriend. I had a premonition that would be a mistake.

    On the ride down it ran fine. I cruised at about 6,000rpm, 80mph no problem.
    I thought I heard that one noisy valve get a little noisier, but thought nothing of it.

    On the ride back was a different story. Halfway back I noticed the noise was significantly louder. I kept going. On the final toll road (408) to get back home, the engine squealed for a second, then quieted. I kept going. When I got to the first tollbooth, smoke erupted from the left side of the engine. Oil was flowing from the cam end cap on the left side. I kept going, stopping asap to get oil. I was only a quart low.

    By the time I got back my left leg was covered in oil, but I'd kept it topped up.

    I took the cam cover off and was horrified to see the left side intake bearing was broken in half. I removed it, and the cam was very deeply scored, as was the ruined bearing. The next one over was bad too, but not as bad. I pulled the left side exhaust cam, and it was fine. All lobes are fine on both cams.

    I have no idea what happened, but this sucks.

    So what do I do next? Do I need a new head? Are the head cam bearing surfaces removable?

    Thanks for the help!
    Tags: None
    #2
    unfortunatly you need another head

    Comment

      #3
      One of the locknuts probably came loose. You need a new head. I know someone who may have one.

      Comment

        #4
        I've seen aluminum heads get line bored before. The machinist then adds steel half-bearings to take up the slack. I think they notch the head a little to keep the plain bearings from spinning.

        I've also seen a GS1150 engine with a bent camshaft. One of the camshaft caps came loose and broke in half. The engine ran with the broken cap and bent shaft but didn't sound too swell.

        Steve

        Comment

          #5
          New head? Line boring? Both interesting ideas. Of course my first question would be which is cheaper. I'm gonna need a new intake cam out of this as well. I'd be interested in finding out how the machinist could line up the tolerances between the head, cam bearings, bearing shells, and the bearing surfaces themselves. I know its technically possible and all, just seems a bit tough.

          Thanks for the tips, and keep em comin!

          Comment

            #6
            Originally posted by Don Lobacz
            One of the locknuts probably came loose. You need a new head. I know someone who may have one.
            Hey Don, you're right one of the locknuts probably did come loose, because both on the broken bearing definitely were when I took it off. Of course that could have happened after it broke too, just from the excess vibration alone.

            Anyway, if you can find a new head, I'd very much appreciate that. Let me know if you get in contact with the guy who has it. Thanks!

            Comment

              #7
              The problem would be to find someone to do the line boreing,+ the cost
              A used head is the cheapest way to repair .Make sure to Replace the block base gasket , make sure the oil passages are not gummed up.
              The problem you have is caused by low oil supply to the head. You could also consider & engine transplant

              Comment

                #8
                I was told that a linebore adds 70 bucks Canadian to the price of a VW diesel head rebuild. This is an aluminum SOHC head with about 5 cam caps. The head is checked for warpage and put into a press to be straightened before boring. I imagine that they use the cam-end plugs spots to line up the boring machine. You'd have to find a set of bearings that match your camshafts before looking into actually having it done. If you can find an 1100 or 750 engine for your bike that is running that would be cheaper than a top end job.

                I heard of another guy that used valve lapping compound on his camshaft. He broke a cam cap so he used the lapping compound to bed in the new-used cap he bought. Seems to be working for him but those engines only go up to about 6000 RPM max.

                Steve

                Comment

                  #9
                  Your entire lower end must be flushed too, to remove any chips.

                  I'd be looking for an engine.

                  Comment

                    #10
                    Originally posted by jimcor
                    I'd be looking for an engine.
                    Don't you mean another bike? Last time I checked finding good engines for these things aint the easiest thing in the world. I've even expanded my search to oil cooled Katana 750 and GSX-r 600, 750, and 1000 motors.

                    I have no idea what I should be paying for one either, but I'm gonna go ahead and guess that market value is way more than I think I should be paying to replace an engine that fragged a head for no reason after being pampered with the best damn oil there is for the last 3,000+ miles. Great investment that was at $6 a quart.

                    Comment

                      #11
                      Originally posted by isaac
                      ... an engine that fragged a head for no reason after being pampered with the best damn oil there is for the last 3,000+ miles. Great investment that was at $6 a quart.
                      Not the oil's fault. And the head did frag for a reason, I'm not in a position to say what the reason is exactly, though. And Isaac, you're going to have to blame yourself, too (ouch, not a flame, really) for continuing to ride the bike when the noises continued to increase. If you had stopped the damage would be less.

                      Comment

                        #12
                        Can't stop or I don't get home and I screw over my business. I don't have a monkey job. I sacrifice things for this.

                        "Well then, be prepared for your bike to randomly tear itself to pieces on the drive home if you got a job that you can't afford to randomly skip out on."

                        Fine, be that way.

                        Comment

                          #13
                          Yep, just sacrificed your bike. Mechanical things dont care what ones schedule is. The engine said, "I'm broke", you said, "I dont have time", and the engine said, "see ya".

                          Earl


                          Originally posted by isaac
                          Can't stop or I don't get home and I screw over my business. I don't have a monkey job. I sacrifice things for this.

                          "Well then, be prepared for your bike to randomly tear itself to pieces on the drive home if you got a job that you can't afford to randomly skip out on."

                          Fine, be that way.
                          Komorebi-The light filtering through the trees.

                          I would rather sit on a pumpkin and have it all to myself than be crowded on a velvet cushion. H.D.T.

                          Comment

                            #14
                            I explained I wasn't flamin' ya man. But when an engine starts making expensive noises, it's time to stop. If you don't, well, like they say: "You paid your money and you took your chances". I really am sorry for you.

                            Comment

                              #15
                              A job like that is good if you can do most of the work yourself buddy.
                              I would say it is bike shopping time too. But look around. You may
                              luck out and find a motor on eBay cheap or somewhere.
                              Hope you can man

                              Comment

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