No valve clearence after an engine strip down

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  • Anonymous
    #1

    No valve clearence after an engine strip down

    Hi All,

    I own a GS850GT 1980

    We have reassembled the engine after a top end strip down (Valve / Cams / Cylinder head / Bores)

    I had to have a small skim off the head because of some scratching and pitting.

    We have decoked the engine and reground the valves in.

    My question is, has anyone ever taken a small grind off the top of the valve stem above the collet to increase valve clearance? Re-shim will be difficult because we don’t know exactly how open the valves are so it is difficult to determine what shim we need. Is this a realistic option?

    Our problem is that now we have reassembled the engine, we have no valve clearance at all most of the valves leaving no compression. Clearance tolerance is between 3 and 8 thousandths of a millimetre we can’t get a 1.5 thousandths gauge through. Some of the exhaust valves are remaining open because they do not clear at all. I am surprised if we have taken so much off the valves during grinding.

    Anyone any ideas?

    Would appreciate your help.

    Mark
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    • Anonymous
      #2
      grinding the tops is a last resort have a look at your shims drop 3 or 4 sizes trial and error if you get down to the thinest then grind the valve tops
      ozman

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        • Anonymous
          #3
          grinding the tops is a last resort have a look at your shims drop 3 or 4 sizes trial and error if you get down to the thinest then grind the valve tops
          ozman

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            • Anonymous
              #4
              No Valve clearance after engine strip down GS850GT

              Thanks for the response Ozman,

              One valve as already been ground at the top and weve managed to get a clearance of 5 thousandths of a Milemeter which is smack on.

              However Im concerned about doing this accross 8 valves as this would mean ?240 pounds in UK if we had to replace them.

              The principle of grinding the valve tops down though is OK and would not cause the engine to self distruct for any reason which I havent considered ???????. The top of the valve is not machine precision squared is this ok?

              Has anyone in the UK got any spare shims for this bike?

              Mark

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                • cbxchris
                  #5
                  be a lot easier to just reshim it. If you do go to tipping the valve stems you had better make sure that you do not let the outside of the retainer touch the inside of the bucket...your keepers will come out and then you will really have a mess. there is a tit that makes contact inside the bucket..measure it and then that will give you a idea how much you can remove.

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                    • Guy
                      #6
                      I agree.......I'd be wary of grinding the tip off the valve stems. Why don't you measure the clearances without the shims or with the smallest shim you have and work out the clearances that way?

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                        • Anonymous
                          #7
                          cbxchris & guy are correct you must be careful if you grind the tops don't just hit them with the angle grinder shims should be avail at any decent suzi dealer not expensive

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