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    Camshaft Markings

    Hi all,
    This is my first post as I've recently purchased a 1982 Suzuki GS750, as a very cheap project bike. The first thing I tested was the compression on all cylinders and it didn't look good (80psi, 120, 60, 60). I popped the head off, and noticed that there are some pitting on the camshaft lobes. It's consistent on ALL of the lobes, and in the same spot. Measuring the lobes they are 1.3724" which is considerably larger than what the service manual suggests (upgraded cams?):

    20170615_095008.jpg

    I am on a bit of a budget, should I let it be? Let me know your thoughts - any input would be fantastic. Thanks guys

    #2
    Is there any other markings on cams?
    1984 GS1100GK newest addition to the heard
    80 GS 1000gt- most favorite ride love this bike
    1978 GS1000E- Known as "RoadKill" , Finished
    83 gs750ed- first new purchase
    85 EX500- vintage track weapon
    1958Ducati 98 Tourismo
    “Remember When in doubt use full throttle, It may not improve the situation ,but it will end the suspense ,
    If it isn't going to make it faster or safer it isn't worth doing

    Comment


      #3
      If it will work I've got some 850 cams you can have. Shipping might be pricey though.
      Roger

      Current rides
      1983 GS 850G
      2003 FJR 1300A
      Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

      Comment


        #4
        Originally posted by Burque73 View Post
        If it will work I've got some 850 cams you can have. Shipping might be pricey though.
        He has a 16-valve 750, the 850 cams will not work.

        Hopefully you only removed the valve cover, not the head, after reading those compression numbers. First thing to do is to check valve clearances. Get those in spec, then you can worry about compression numbers.

        Ideally, compression check should be done on a warm engine, but if you can't warm it up, you can still get a decent idea of balance and overall condition. Just be sure to have all spark plugs OUT and hold the throttle wide OPEN while cranking the engine.

        Do you know anything about the history of the bike? Has it been used regularly until recently? If the compression numbers are somewhat even and the engine has not been run for a while (several months?), and you can get it to run, just give it an Italian Tune-up (google that) and run it several hundred miles and check the compression numbers again.

        I don't have a manual available at work to compare your cam dimensions, someone else will have to let you know if it's an aftermarket cam.
        .
        sigpic
        mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
        hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
        #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
        #2 son: 1980 GS1000G
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        Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
        (Click on my username in the upper-left corner for e-mail info.)

        Comment


          #5
          Yes..check valves and go beat the scitznit out ofit a while..then recheck compression on a warm engine and hold the throttle wide open when you crank it.
          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.

          Comment


            #6
            i talked to an engine rebuilder, my cams looked worse than yours.
            Expected him to laugh and declare my cams ready to scrap.

            All he said was sand the sharp edges down on the pitted lobes, the pitting holes
            will carry oil and do not pose any problem at all.
            Rijk

            Top 10 Newbie Mistakes thread

            CV Carb rebuild tutorial
            VM Carb rebuild tutorial
            Bikecliff's website
            The Stator Papers

            "The thing about freedom - it's never free"

            Comment


              #7
              Originally posted by Steve View Post
              He has a 16-valve 750, the 850 cams will not
              .
              Oh, so did all 750's have 16 valves? Some have mentioned using a head from an 850 on a 750. I'm not familiar with all the models yet but I'm picking up quite a bit.

              It just doesn't make sense that a head with 16 could be swapped for one with only 8.

              Sorry to sidetrack the thread here.
              Roger

              Current rides
              1983 GS 850G
              2003 FJR 1300A
              Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

              Comment


                #8
                8 valvers prior to 1980
                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.

                Comment


                  #9
                  Thank you. I Learnt sumthin!
                  Roger

                  Current rides
                  1983 GS 850G
                  2003 FJR 1300A
                  Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                  Comment


                    #10
                    Wow, you guys are fantastic. Especially you Burque, very generous to offer your cams!!
                    Originally posted by Steve View Post
                    Hopefully you only removed the valve cover, not the head, after reading those compression numbers. First thing to do is to check valve clearances. Get those in spec, then you can worry about compression numbers.

                    Do you know anything about the history of the bike? Has it been used regularly until recently? If the compression numbers are somewhat even and the engine has not been run for a while (several months?), and you can get it to run, just give it an Italian Tune-up (google that) and run it several hundred miles and check the compression numbers again.
                    .
                    Yes the first thing I did after checking the compression was to check the valve clearances. Unfortunately they were all within spec, so I popped off the head I did make sure that the throttle was wide open and all spark plugs are out.

                    I know very little about the history of the bike. But I know that it hasn't been running for a while, as the wiring is completely apart.

                    Here some pictures of the piston and valves:
                    20170614_225745.jpg
                    I can only post 1 picture?! Give this a shot:


                    Comment


                      #11
                      Hey, you're welcome M. G. Not a big deal though as I stripped the cams and all other internals from a head with stripped spark plug threads and a botched repair job that made it useless.
                      Roger

                      Current rides
                      1983 GS 850G
                      2003 FJR 1300A
                      Gone but not forgotten 1985 Rebel 250, 1991 XT225, 2004 KLR650, 1981 GS850G, 1982 GS1100GL, 2002 DL1000, 2005 KLR650, 2003 KLX400

                      Comment


                        #12
                        When it has low numbers, always do a leak down test before pulling it apart. This will tell you where it is leaking from and how much.
                        Speed Merchant
                        http://www.gszone.biz

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