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gs850 engine rebuild, tight spot in rotation

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    #1

    gs850 engine rebuild, tight spot in rotation

    Hi -

    I'm reassembling an '80 gs850 engine, and now that I'm to the point of adjusting the valve clearances, when I rotate the engine I'm finding a tight spot in the rotation

    It occurs at the two rotation points just as a pair of pistons is coming toward the top of the stroke. I know knothing was tight before I installed the cylinders and top end, and I've got it in neutral w/ the clutch disengaged to be sure it's not in the transmission. So, I'm pretty sure it's related to the pistons or head. I don't remember whether I rotated the engine at all after I put on the pistons and cylinders before I put the head on - I don't think I did, so can't say for sure if it was tight at that point.

    It's not completely binding, just gets a little tighter at two spots in the rotation - if I push a little harder on the wrench then it keeps on turning and seems to jump past the tight spot, but it takes about 25 lbs of torque to do it. No noticeable noises except the slight noise of everything suddenly turning again. I have the spark plugs out, so it's turning against compression.

    So, probably I'll take the head and cylinders off to test. But, just wanted to see if anybody has any experience/suggestions with this first
    Tags: None
    #2
    Check the timing. You might be tapping a valve.
    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.

    Comment

      #3
      that's what I was afraid of, and seems to be the case. thought I had the timing dead on, but apparently not or else the valve clearances are way too tight.

      oh well, I really didn't intend to put it back in the frame today . . . :-)

      Comment

        #4
        Originally posted by micahcondon View Post
        that's what I was afraid of, and seems to be the case. thought I had the timing dead on, but apparently not or else the valve clearances are way too tight.

        oh well, I really didn't intend to put it back in the frame today . . . :-)
        If the valve timing is out, using a torch you should be able to see the valves touching the piston, through the spark plug hole! If there is adequate piston to valve clearance, you need to investigate other areas. Have you done any radical mods to the engine?
        :) 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
          flashlight torch, not MAPP gas.

          Comment

            #6
            Originally posted by uudfourty View Post
            flashlight torch, not MAPP gas.
            That one gets me every time.
            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.

            Comment

              #7
              Thanks - it was the valve timing, retimed it and it's fine now. Now just need to see if I bent any of the valves - I was planning to do a compression test anyway before I fire it up

              Comment

                #8
                Will twenty-five pounds of tourque bend a valve? Maybe but probably not.
                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.

                Comment

                  #9
                  Now, for the really curious ones out here...which cam was it, how many teeth off was the cam, and which direction?

                  Just something to toss into the old memory bank. Would be nice to know that 1 tooth or 2 teeth off might be OK, but 3 teeth definitely touches. That sort of thing. 8-[

                  .
                  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
                  Family Portrait
                  Siblings and Spouses
                  Mom's first ride
                  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

                    #10
                    Originally posted by Steve View Post
                    Now, for the really curious ones out here...which cam was it, how many teeth off was the cam, and which direction?

                    Just something to toss into the old memory bank. Would be nice to know that 1 tooth or 2 teeth off might be OK, but 3 teeth definitely touches. That sort of thing. 8-[

                    .
                    Steve, You have posed some interesting questions. micahcondon could run a book on this!!
                    Ok, I should have suggested using a flashlight instead of and open flame (torch). But hey, he hasn't even got the carbs or tank fitted yet so the torch might still be a safe option. You need to be careful not to singe your eyebrows though!

                    My bet is on the exhaust valve. If it were the inlet valve, it would be still advancing (opening) after TDC and trying to jamb tighter into the top of the piston. On the other hand, the exhaust valve is continuing to close after TDC. On my 850 cams, the opening and closing figures between them both differ by only 0.5degs at TDC.

                    So, my bet is the exhaust cam being ???? teeth advanced!!
                    Last edited by 49er; 04-29-2008, 01:51 AM.
                    :) 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
                      the exhaust cam was off, I think maybe two teeth, due to slack in the chain when I first timed it. So, since the intake cam was still timed correctly with the exhaust , it was off by the same amount. Not sure which one was hitting

                      Comment

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