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Tensioning cam chain

Discussion in 'XJ Technical Chat' started by Alain, Sep 10, 2016.

  1. Alain

    Alain Member

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    I have a 81 xj650. it's making some kind of 'noise' sounding like the cam chain tension has to be checked. I have a Haynes manual and it says to open up the crankshaft case on the 'left' but i'm not sure which one it is. I opened up the 'rear brake side' and there was nothing there. i'm assuming i'm looking at the crankcase shaft cover on the 'gear side'.

    also, can anyone give me instructions on how to do this? with pics? I'm reading the Haynes manual but it's a bit vague.
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    it is left side as you sit on bike. there will be a mark on the rotor a "C"that you line up with the timing pointer.
    then you loosen the camchain tensioner and re torque.

    the bolt with the lock nut is the one to be loosened
     
    Last edited: Sep 11, 2016
  3. XJ550H

    XJ550H Well-Known Member Premium Member

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    this is for a 550 check your torque specs for a 650\

    1 remove left side cover

    upload_2016-9-11_8-55-6.png upload_2016-9-11_8-55-38.png
    upload_2016-9-11_8-56-13.png
     
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  4. DenCon509

    DenCon509 Member

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    Engine cold, warm, hot - what is best?
     
  5. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    Cold.
     
  6. Alain

    Alain Member

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    I was looking at this thing last night and was wondering how the hell do you adjust tighten the stopper bolt and nut with a torque wrench being in such a odd position. I'm hoping it's a quick adjustment/check but i think i might have to remove my carbs :(
     
  7. dkavanagh

    dkavanagh Well-Known Member Premium Member

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  8. Ketchup

    Ketchup Member

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    @XJ550H @joe elliff @k-moe

    Digging up an old thread to say, once more, thank you. Apparently my reading and apprehension skills aren't what they used to be as this process was overlooked entirely despite seeking it. At least I was able to locate it here! Thank you in advance all,


    After having read the service manual, I do however have an inquiry regarding the "Front Cam Chain Guide" on the 1981 XJ550 Maxim (5k5). Can this component [figure 1] be replaced without much disassembly?

    Suspecting my chain tension to be too great - not much slack on the "Center Chain Guide" [figure 2].

    Dialogue Legend
    "Too great" = Improper torque setting by PO; chain seems tight by feel in comparison to current/former manually tensioned machines
    "Not much slack" = less than 4mm if attempting to pull cam chain upward. Probably closer to 3mm.
    "Without much disassembly" = Thinking roughly similar amount of teardown for valve shim process. I.E. - not pulling the engine or splitting cases.
    Chain Tensioner Status = Tensioner Bolt has approximately 3-4mm of adjustment remaining with locknut.

    Ideally, I would like to replace both/all chain guides and set proper tension.

    Additionally, is there any sort of rough estimate as to how far that cam chain should pull up off the center chain guide?


    Figure #1. Front Cam Chain Guide
    Screen Shot 2018-03-13 at 9.37.06 AM.png


    Figure #2. Center Chain Guide
    Screen Shot 2018-03-13 at 9.40.40 AM.png
     
    Last edited: Mar 13, 2018
  9. XJ550H

    XJ550H Well-Known Member Premium Member

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    set the crank to proper location indicated by mark.
    you use a a deep socket on the lock nut to loosen it. then back out on locking bolt .
    the spring pushes the rod forward on the chain then tighten bolt and nut .
    nothing you tighten will make the cam chain tensioner over tight on the chain all the tensioning is done by the spring
    set the bolt to torque spec then the lock nut to torque spec.

    4mm beetween bolt head and nut is normal
    exploded view of tensioner
    cct.JPG
     
    Last edited: Mar 13, 2018
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  10. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    The cam chain guides can be fully removed with the head in place. You'll need to remove the fuel tank, and the valve cover for access.
    Keping the cam and crank set to the timing mks as describd above, remove the cam chain tensioner (you will want to have a new gasket on hand), then the cam chain guides can be removed. To remove the top chain guide you will need to either unbolt the cam sprockets from the cams, or break the cam chain and fit a new chain.
     
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  11. XJ550H

    XJ550H Well-Known Member Premium Member

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    if you removed or backed out the adjuster screw more than 1-1/2 turns the assembly may have come apart. that may over tighten chain if that is possible large spring has a lot of force
    expl assembly.jpg internal.jpg
    on first photo you can see the shinney spot where screw makes contact and holds in position.

    photo is missing a damper washer # 16 between small spring and face of internal plunger

    this is the recess the smaller external plunger rides in, on chain guide
    divot.jpg

    the face of large internal plunger is almost flush with cct body and at full extended position is out about equal to the diameter of the face of plunger
     
    Last edited: Mar 13, 2018
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  12. Ketchup

    Ketchup Member

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    Thank you for clarifying, @XJ550H - This is perfectly concise. This means my cam chain tensioner is certainly performing its role correctly, and with a rather robust spring.

    Referencing the gasket - valve cover gasket? I had just replaced that upon doing the valve shims a few weeks back courtesy of...Chacal! Essentially, similar prep to get the top end off with the exception of camshaft sprocket removal. Got it. I'd say getting most of the top end off is less than a 5 minute job without powertools - Just AC/DC. Would you say there's anything I should watch out for? Seems like worst case scenario we're dropping something into the engine case. Thinking I'd want to matchmark the sprockets to the camshaft, and the sprockets to the cam chain to insure proper re-installation.

    Understood - do not want to back out adjuster screw more than 1.5 rotations.


    Would it be safe to simply remove the entire tensioning apparatus in lieu of replacing the cam chain guides? Or will this allow the cam chain tensioner to decompress and drop he's guts into me motor? (humor). Again, thank you both for the detailed responses - much much appreciated. You all rock!
     
  13. XJ550H

    XJ550H Well-Known Member Premium Member

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    I thought about the statement about turning bolt out "to Far" . the way the cam chain tensioner works for it to come apart in the motor your chain would have to be very over stretched and beyond adjusting. and would not over tension the chain.
    cam chain tensioner keeps your motor in proper valve timing. without the tensioner the chain slack would move from front to back of cams depending on if you were opening or closing the throttle. it also keeps the chain from cutting through the jugs after it destroyed the guides which is one of the reasons the guides are in there too.

    i still would not turn it more than 1.5 turns out

    you can remove the tension assembly to replace tensioner gasket so it will not fall into motor,
    and that is the gasket K-moe was talking about.
     
    Last edited: Mar 13, 2018
  14. Ketchup

    Ketchup Member

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    Again - perfectly clear and well received. Sounds like I will take some time and play arts and crafts with the fel-pro gasket material.

    Additionally, based on your attached images (thank you by the way - saved those), it doesn't seem like there's enough adjustment-screw to compress the spring far enough to exert more than spring-only-tension.

    Take-aways:
    1. Replace cam chain guides
    2. Replace cam chain tensioner gasket
    3. Don't unscrew more than 1.5 turns and drop junk into engine
    4. Spend more time riding bike - than on XJBikes (just kidding..)
     
  15. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    To clarify: the cam chain tensioner uses a paper gasket. It won't likely survive when the tensioner is removed.
     
  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    the adjustment screw is just to hold rod in place if you look at second photo you will see the flat cut into the rod . adjuster screw is just a set screw. loosen it the spring pushes assemblies forward tighten it to set position.
    internal.jpg
     

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