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    Need help, cracks in combustion chamber?

    I took of the head yesterday and today after a good cleaning i noticed what looks like cracks in the head near the spark plug hole.
    i'm hope i'm mistaken and they are not cracks but some casting marks or something.
    they appear the same shape and location on both cylinders. i took off the head of my second bike and although it had lot of carbon deposit it looks like there are the same "cracks" on it as well.
    I tried to take pictures i hope they're clear, these are the two cylinders.




    #2
    The two look like the same marks in the same spots. Right now I am thinking casting marks. They didn't have to be perfect and this seems like the case to me anyway.
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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      #3
      I had a head on an 1100e 16v and it did not seem to hurt anything

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        #4
        Originally posted by posplayr View Post
        I had a head on an 1100e 16v and it did not seem to hurt anything
        Sorry, not sure i understand. do you mean you had the same thing on a 16V head?

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          #5
          Originally posted by eran_k View Post
          Sorry, not sure i understand. do you mean you had the same thing on a 16V head?
          Yes same cracks on at least one cyclinder ; put it back together with no issues.

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            #6
            I build heads & those cracks make the heads junk. If I get one that has a lot of money in it, porting wise, we will weld them up & fix them. Cylinder heads crack between the plug hole & exhaust seats due to heat, detonation, or both. You can keep running it if you want but check to see it isn't leaking. To ME, cracks like that make need for a replacement. Ray.

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              #7
              You can check to see if the head leaks through the cracks by doing a leakdown test & spraying soapy water around the spark plug hole when you are leaking it. Of course, this needs to be done with the head on the motor & torqued like it is ready to run. Ray.

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                #8
                this is common on turbo 16v. heads...
                i still have a record setting star head from 87 that looks baddd around the plug holes but still performs.
                run it till it won't run no more!

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                  #9
                  Seen cracks you can fit a dime into,
                  I suppose once you have the spark plugs out you can see if the crack has propagated up the threads. The spark plug should seal it though. You could set the head upside down and fill the combustion chambers full of solvent or something to see if it seeps out. The valves might leak more than those cracks.
                  I'd ignore them.
                  As long as they don't go I to the water jacket it should be fine.
                  GSX1300R NT650 XV535

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                    #10
                    This is a common problem on the older twin 8 valve engines. I think after 83-84 they made a change to the head that fixed that problem.
                    Some have even seen it crack bad enough to leak out the plug hole and puff like a steam engine. I'd use a different head if possible, or run it until it gets bad.
                    Stephen.
                    1981 GSX540L "Frankintwin"
                    1989 GS500E Resto-mod .

                    400 mod thread
                    Photo's 1

                    Photos 2

                    Gs500 build thread
                    GS twin wiki

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                      #11
                      water jacket??
                      just checking

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                        #12
                        Just a guess, you think these cracks form from running a cold engine hard and heating it up too fast?
                        http://img.photobucket.com/albums/v5...tatesMap-1.jpg

                        Life is too short to ride an L.

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                          #13
                          Originally posted by Mekanix View Post
                          This is a common problem on the older twin 8 valve engines. I think after 83-84 they made a change to the head that fixed that problem.
                          Some have even seen it crack bad enough to leak out the plug hole and puff like a steam engine. I'd use a different head if possible, or run it until it gets bad.
                          Correct - and it's what you were warned against too on your one...

                          I'd doubt if there's a lot of heads in the middle east and your chances of getting a good one off ebay are probably pretty slim. From personal experience they will go for a long while with cracks like that. it is possible to machine out the inserts and weld/remachine etc but it's a difficult and costly job....never know, someone here may have a good head.

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                            #14
                            Well i went to a specialist machine shop today that only do heads, the guy inspected the head and said it's good. so with that and the opinions here i'm going to use it for as long as it'l work.
                            Thanks
                            Eran

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                              #15
                              Two better shots,each one is a different cylinder



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