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Valve shim diameter

Discussion in 'XJ Technical Chat' started by Shaynus, May 21, 2015.

  1. Shaynus

    Shaynus Member

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    Hi All
    Am working out what shims I need, but now can't remember if they are 25mm or 28mm diameter (or something else entirely!) - doh!
    I'm away from the bike for a bit and was going to see which ones I need to get.
    It is a 1984 XJ750
    Cheers
     
  2. Toomanybikes

    Toomanybikes Well-Known Member

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    Honda are 25 so they should be 28
     
  3. Polock

    Polock Well-Known Member

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  4. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    doesn't matter what honda are.

    the xj airheads are 29mm, as Polock said. (The Ventures have 25mm shims......and yes, I have a pool for them, too!----LOL)

    29mm. But you can't just order 29mm shims.....you need to know EXACTLY what thickness you need. In order to do that, you need to have already done your clearance check, pulled the shims to record what sizes are already in there, and then have done the math or checked the chart to see what sizes you need to change to.

    dave
     
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  5. jokidd82

    jokidd82 Member

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    Since we are on the subject of shim do any of you have a giant variety of them. I need a few under 260. I have a lot of 270s and 275s but no clearance yet.
     
  6. jokidd82

    jokidd82 Member

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    29mm of course.
    And sorry to thread jack
     
  7. XJ550H

    XJ550H Well-Known Member Premium Member

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    Hogfiddles How does one get into your pool ?
     
    Last edited: May 21, 2015
  8. Toomanybikes

    Toomanybikes Well-Known Member

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    Just took a stab at size I know they where bigger just didn't want to go to toolbox and check for sure,was half awake at ungodly hour
     
  9. Shaynus

    Shaynus Member

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    Yep, I've measured the clearances, recorded the corresponding shim thickness, just forgot to check the diameter of them!
    Just need to find 5 minutes to sit down and work out which ones I can shuffle around and what new thicknesses I need to get.
    Thanks everyone.
     
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  10. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Tell me what sizes you need, and I look to see what I have. No need to measure diameter..... They're all 29mm unless you have a maximX
     
  11. XJ550H

    XJ550H Well-Known Member Premium Member

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    is this done on a swap and postage basis?
     
  12. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Check your inbox
     
  13. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    SC sent...
     
    Last edited: May 21, 2015
  14. Shaynus

    Shaynus Member

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    Thanks for the offer, but I'm on the opposite side of the world from you so I will try to source some from this continent, but if I have no luck I may just take you up on your offer :)
     
  15. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    I'll trade you a 29mm opal for a 29mm shim
     
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  16. Shaynus

    Shaynus Member

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    LOL!
    That would be worth more than my whole bike!
    Then again, a six pack of beer wouldn't be worth much less than it either!
    ;-)
     
  17. wwivhobbit

    wwivhobbit New Member

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    What size are the Maxim-X shims? I'm sure my bike needs to be reshimmed as it's got 25k miles on it. I can't seem to find what diameter shims to look for tho!
     
  18. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Maxim asked Shims are different… They are much smaller and are a little cap that goes on top of the valve stem, underneath the bucket
     
  19. Simmy

    Simmy Well-Known Member

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    As Hogfiddles stated, shims are under the bucket, you have to pull the camshafts on the X to change .
    If I were you and riding season is here, I would take the cam cover off and measure your clearances.
    With any luck you may be good to go. If a few are tight I would button it back up and ride until you have a chance to tackle this.
    Len is fast shipping but you're going to be down for a week at minimum.
    You should always synchronize your carbs after a valve adjustment so prepare yourself for that also.

    If you find any valves with zero clearance do not ride, proceed right to the shim swap.
     
  20. Toomanybikes

    Toomanybikes Well-Known Member

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    Tight shins have been a major cause for “X” model demise. With such a small valve they can overheat quickly and cause engine total failure. There are more than a few that have been parted out because spare engines are hard to find.
    There is one near me that otherwise is a 9.9 out of 10 but for a broken piston and rod explosion.
     

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