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procedure for zero valve clearance

Discussion in 'XJ Technical Chat' started by seca550RK, Jun 4, 2014.

  1. seca550RK

    seca550RK Member

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    Hey everyone,
    I am looking for suggestions for dealing with the 2 valves that have zero clearance :( I want to get a measure on them so I can order shims. Is it possible to switch a thinner shim in without messing up the cams since this would entail rotating the cams without a shim at some point.
    Thanks!
     
  2. lacucaracha

    lacucaracha Member

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    Yeah that's a tough one. I had "zero" clearance on a couple when I first got my bike. Mess around with the cam angle to see how far off it needs to be in order for you to get something under it.

    If it's not much, assume it's zero, and adjust accordingly.
     
  3. tskaz

    tskaz Active Member

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    It is NOT recommended that you rotate the cam lobe on a bucket without a shim in place.

    However, with careful observation you should be able to see which shim you can remove and replace without rotating on the empty bucket.

    EXAMPLE:
    When number one intake is open, number 3 exhaust is open. If you had two shim hold down tools you could remove and swap those at the same time without any ill effects, unless of course the numbers are way different. Don't swap out a 245 with a 295, for example.

    There is always one exhaust valve open when there is an intake valve open.

    This won't work if both shims you need to swap are on the same side.
     
  4. pillowmaster50

    pillowmaster50 Member

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    If I were you, I'd order a shim that's about 5 or 6 sizes thinner, then swap it out on the ones that are 0 clearance. Make sure you have a good set of feeler gauges and you know how to use them! Also, it may be a good idea to pop off the head to inspect for burnt valves, and maybe do a valve lap job.
     
  5. seca550RK

    seca550RK Member

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    I'll go check it out and see if I can remove one of the others, I don't want to wait for the order of a thin one just to get a measure.
    How hard is it to "pop the head off" I'm still a little new to mechanics so I don't want to get in over my head. Maybe just a compression check to see how its fairing?
    h
     
  6. tskaz

    tskaz Active Member

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    Definitely do a compression check.

    Taking the head off is quite a bit of work, but not a difficult job. But post the numbers from the compression check first.
     
  7. pillowmaster50

    pillowmaster50 Member

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    Compression check will be low if the valves aren't closing all the way :) if you're willing to teach yourself more about working on motorcycles, take the head off. You will probably run into unforeseen issues that will cost some money and will require waiting for parts... If that isn't too appealing to you, then just leave the head alone and hope for the best. You will absolutely need to get a valve shim of known thickness into the buckets that have 0 clearance. Swapping shims all around could get tedious and time consuming; make sure to keep good notes! (that's why I suggest getting your hands on a spare thin one).
     
  8. seca550RK

    seca550RK Member

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    I think I'm about to get a spare one afterall. Maybe I'll dig into the carbs while I'm waiting if I'm feeling man enough.
    I'll look to borrow something for the compression check just to see where I'm at. I thought the previous owner was taking care of the bike, but obviously the valve clearance was neglected.
     
  9. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Stop stop stop.

    Are they intake or exhaust valves? "Read" what's in there now. Go two sizes down if an intake valve and three sizes down if an exhaust valve.

    (Two sizes gains you .10mm and an intake only needs to be at .11 to be in spec; three sizes down will gain you .15mm where you're looking for .16mm.) Since "zero" probably isn't completely zero, that should put you in spec; if not then you'll have a couple of extra shims for swapping, and be close.

    DO NOT pull the head just because you found a couple of dead tight valves. DO get them in spec, then run a compression test. (Dead tight valves will affect your compression test results.)

    If you pull a motor apart hastily, you lose all ability to diagnose what issues it may or may not have had prior. You're nowhere near "pull the head" stage; at this point there is no reason.
     
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  10. RPHRIDER

    RPHRIDER Member

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  11. MiCarl

    MiCarl Active Member

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    This is very good advice. Let me add to it:

    If they're truly less than 0 the valves/head are likely damaged.

    Shims are inexpensive. For an intake measuring 0 I'd get one -0.10 and -0.15. For an exhaust measuring 0 I'd get one -0.15 and -0.20. With that combination you're likely to have a shim that brings you into spec. Sure, it'll cost you and extra $20, but you'll save some time and eliminate the temptation to do something less than smart.
     
  12. seca550RK

    seca550RK Member

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    Thanks Fitz, its one exhaust and one intake, so I'll take that advice and order the shims accordingly. I also have some borderline cases . I couldn't find a metric set so my shims read .102mm and next .127mm which is unfortunate for measuring the .11mm clearance. Also .152 and .178 for the exhaust. Should I leave these for next time or risk overshooting the clearances?
     
  13. seca550RK

    seca550RK Member

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    I forgot to add the smallest feeler was .38 so its likely not a total zero. I couldn't find something smaller without ordering online.
     

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