1. Some members were not receiving emails sent from XJbikes.com. For example: "Forgot your password?" function to reset your password would not send email to some members. I believe this has been resolved now. Please use "Contact Us" form (see page footer link) if you still have email issues. SnoSheriff

    Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

Valve clearance questions

Discussion in 'XJ Technical Chat' started by jvswan, Jan 23, 2010.

  1. jvswan

    jvswan Member

    Messages:
    205
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Havelock, NC
    Hey all,

    I had the valve cover off to check the timing on my XJ700XN, and I went ahead and checked the clearances since I was in there. I found an interesting pattern. All exhaust valves (8) were within spec and ranged between .006" and .008". BUT, the intake valves (12) were ALL less than .002".

    Currently I'm having a lot of trouble with my bike. It won't start, let alone run. Anyway, I just thought it was odd that all the valves on one side were too tight and all the valves on the other were just right.

    Is that odd? Normal? Is there any chance that this might help me diagnose my problem?
     
  2. wizard

    wizard Active Member

    Messages:
    5,282
    Likes Received:
    26
    Trophy Points:
    38
    Location:
    DEVON ENGLAND
    Have you checked the compression?
     
  3. jvswan

    jvswan Member

    Messages:
    205
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Havelock, NC
    Well, here's the thing. I had it at a mechanic. Among other things, he told me the compression was 40-50 on all four dry, and 140-150 on all four when done wet (bit of oil in the cylinder). He also told me my timing was way off (http://www.xjbikes.com/Forums/viewtopic/t=22691.html), so I took the valve cover off and here we are.

    I don't have a compression gauge of my own, and in any case, I've removed the coils, so I haven't done a compression test yet.

    And yeah, I know the discrepancy between the two compression tests indicates rings or something in the cylinder. I'm honestly not sure why he told me it was timing. I'm just hoping the problem might be something more accessible for a DIY garage mechanic such as myself.
     
  4. RickCoMatic

    RickCoMatic Well-Known Member

    Messages:
    13,843
    Likes Received:
    66
    Trophy Points:
    48
    Location:
    Massachusetts, Billerica
    Disregard everything that guy told you.
    He was out to shake you down.

    Do your own Comp Test ... and Do it right.
    Get some Accurate Intelligence instead of Lies and proceed one step at a time.
     
  5. jvswan

    jvswan Member

    Messages:
    205
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Havelock, NC
    OK. Got it. I'll do compression test this week, as soon as I can find someone with a compression gauge.

    Thanks!

    BTW, in the last post you said disconnect the TCI? Is that right? So, all plugs out, fully charged battery, and disconnected TCI?
     
  6. wizard

    wizard Active Member

    Messages:
    5,282
    Likes Received:
    26
    Trophy Points:
    38
    Location:
    DEVON ENGLAND
    You should remove the air filter & have the throttle wide open when checking the compression & just allow 4 strokes per pot.
     
  7. RickCoMatic

    RickCoMatic Well-Known Member

    Messages:
    13,843
    Likes Received:
    66
    Trophy Points:
    48
    Location:
    Massachusetts, Billerica
    Well, ... seein' as how you got a 20 Valve Max-X and will need to Monitor Compression ... annually.

    SEARS ...
    Either the Craftsmen
    or
    The Action Brand

    $29.00 or less on saale.
     
  8. bigfitz52

    bigfitz52 Well-Known Member Premium Member

    Messages:
    21,283
    Likes Received:
    419
    Trophy Points:
    83
    Location:
    Rural SE Michigan 60 miles N of Motown
    In answer to your original question: the valves tighten with wear; yes it's very possible for all the intake valves to be worn-in more than the exhaust valves. They're quite a bit smaller than the exhaust valves.

    How many miles on this bike? Do you know if the valves have ever been checked/adjusted previously?

    Until you get the valves in spec (use a metric gauge; .006" is actually too tight if you do the math) don't worry about compression testing. Tight vaves are opening way too soon, and will throw it off big time.

    Rick is right about the compression gauge.
     
  9. PainterD

    PainterD Active Member

    Messages:
    2,649
    Likes Received:
    4
    Trophy Points:
    38
    Location:
    St. Cloud, Minnesota
    Yes the valve wear is not all the same for various reasons. Mine were irratic also when I checked mine. Most Yamaha dealers will swap them for yours if you need different sizes.
     
  10. jvswan

    jvswan Member

    Messages:
    205
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Havelock, NC
    OK. Thanks for the suggestion for the pads. I'll see if I can find a dealer locally who might be willing to swap them out.

    Since I've got the valves exposed anyway, I guess I'll work on getting them adjusted, then I'll check the compression.

    Thanks again.
     

Share This Page