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Thread: Primary Chain Adjustment Question

  1. #1
    Senior Member GregoXB's Avatar
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    Primary Chain Adjustment Question

    I'm trying to dial in the adjustment on my primary chain. Did a stator swap a month back and I am trying to dial in the tension. I was hearing a knock and I found about 1 inch of play so I tightened it a bit down to 1/2 inch of play, while cold. I am getting a much milder knock on occasion now.

    My question is: when testing for play how much force should be applied to the chain? Obviously I am adjusting it thorough the primary inspection cover, so all you can get in there is a digit. I can press it till it stops but then, if apply more force, I can press it up some more. Depending on how hard I push, the slack can be measured differently.

  2. #2
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    Apply pretty big force, but make sure it does not affect you measuring method, keep you measuring tool steady and leveled. I would say 3-5 kilos (6-10lb) force is OK.

    Also make sure you set minimal slack in tightest spot. I shift on 5th gear and turn rear wheel to turn the engine to measure chain slack in a few spots .


    Remeasure chain slack in a few spots after tightening chain tensioner since tightening can affect chain slack.

    Once you have set minimal slack in tightest spot measure slack in a few spots and find biggest slack and compare it with biggest allowed slack according service manual. If it is bigger than maximal allowed slack, you have to replace the primary chain.

    I am assuming you inspected chain tensioner boot while replacing stator and it was good.
    Last edited by TPEHAK; 09-20-2017 at 08:32 PM.

  3. #3
    Senior Member Silverrider's Avatar
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    http://buellmods.com/#TabbedContent1.11
    PRIMARY CHAIN
    INSPECTION
    See
    Figure 1-
    31
    . Measure primary chain tension through the
    inspection cover opening. Adjust primary chains not meeting
    vertical free play specifications.
    1.
    See
    Figure 1-
    31
    . Remove two fasteners with captive
    washers and primary chain inspection cover with gasket
    from primary cover.
    2.
    See
    Figure 1-
    32
    . Check primary chain tension by meas-
    uring vertical free play.
    a.
    Measure vertical free play through chain inspection
    cover opening.
    b.
    Rotate engine to move primary chain to a different
    position on sprockets.
    c.
    Measure vertical free play several times, each time
    with primary chain moved so that the measurement
    is taken with sprockets rotated to the tightest chain
    position.
    3.
    The tightest measurement taken in the previous step must
    be within the specifications listed in T
    ab
    le 1-
    11
    . If neces-
    sary, adjust as described under 1.11 PRIMAR
    Y CHAIN,
    Adjustment
    .
    NOTE
    The initial primary chain vertical free play specification used
    at the assembly plant is 1/4-1/2 in. (6.4-12.7 mm) with a cold
    engine. The
    1/2 in.
    (6.4 mm
    ) minimum is only allowed at the
    absolute tightest point in the drive, as measured with special-
    ized factory equipment. If a chain has less than 1/4 in. (6.4
    mm
    ) vertical tension (with a cold engine), adjust tension to the
    "field" specification of 3/8-1/2 in. (9.5-12.7 mm). The looser
    specification will avoid overtightening, which might otherwise
    occur during adjustment using "non-factory" equipment and
    methods.
    4.
    See
    Figure 1-
    31
    . Install primary chain inspection cover
    and
    new
    gasket to primary cover using two fasteners with
    captive washers. Tighten fasteners to
    84-108
    in-lbs
    (9.

  4. #4
    Senior Member GregoXB's Avatar
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    Thanks guys. I'll follow those steps.

  5. #5
    Senior Member Cooter's Avatar
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    I go a little old skool with this adjustment.

    With the bike idling in neutral, I back off the adjuster until you hear the noise get louder (rackety noise, it's obvious), then tighten slowly. You will hear it get quiet and then louder again (a more of a buzzing noise, still obvious) then back off 1/2 that distance.

    IMO, it eliminates the question of tight spots in the primary chain and it's really fast and easy to do. I check them after JIC, but have always been within spec after adjusting that way. YMMV

  6. #6
    Senior Member MakingPAIN's Avatar
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    Quote Originally Posted by Cooter View Post
    I go a little old skool with this adjustment.

    With the bike idling in neutral, I back off the adjuster until you hear the noise get louder (rackety noise, it's obvious), then tighten slowly. You will hear it get quiet and then louder again (a more of a buzzing noise, still obvious) then back off 1/2 that distance.

    IMO, it eliminates the question of tight spots in the primary chain and it's really fast and easy to do. I check them after JIC, but have always been within spec after adjusting that way. YMMV
    That is now how I will check mine. I always fought with mine, a little to tight, turn it over a little to loose.

  7. #7
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    motorcycle "primary drive chain" systems have been around 90 years now as have the simple as-per-manual adjustment procedures. can't be any simpler or concise than those procedures.....performed at room temp. what i typically see is destruction of internal primary drive components AND stripped out primary case threads that hold the primary chain shoe adjuster threaded shaft which is a real bitch to repair. from constant fiddling. do as you please...follow any lead....adjust till your heart's content....but if you experience substantial loose/tight fitment thru the entire run of the primary chain you have not only a chain that is defective but also a worn input shaft bearing assembly. a serviceable chain and internal components adjusted as-per-manual will never "knock". the primary on some XB's will emit a pleasant whirring noise...but never a knock. if yours does you have something awry internally that needs addressed.
    Last edited by user_deleted; 09-21-2017 at 09:26 AM.

  8. #8
    Senior Member GregoXB's Avatar
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    Quote Originally Posted by lunaticfringe View Post
    motorcycle "primary drive chain" systems have been around 90 years now as have the simple as-per-manual adjustment procedures. can't be any simpler or concise than those procedures.....performed at room temp. what i typically see is destruction of internal primary drive components AND stripped out primary case threads that hold the primary chain shoe adjuster threaded shaft which is a real bitch to repair. from constant fiddling. do as you please...follow any lead....adjust till your heart's content....but if you experience substantial loose/tight fitment thru the entire run of the primary chain you have not only a chain that is defective but also a worn input shaft bearing assembly. a serviceable chain and internal components adjusted as-per-manual will never "knock". the primary on some XB's will emit a pleasant whirring noise...but never a knock. if yours does you have something awry internally that needs addressed.
    So since I heard a knock, can there be something amiss in my primary?

  9. #9
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    H-D small and big twins(V-rod excepted) and buell XB's have a 720 crank.
    ducatis have either a 90 degree or 360 degree crank depending on model.
    ducatis will "knock" if the idle speed is set too low or the TB's are out of synch.
    XB's will never "knock" unless there's something wrong internally.

  10. #10
    Senior Member GregoXB's Avatar
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    Quote Originally Posted by lunaticfringe View Post
    H-D small and big twins(V-rod excepted) and buell XB's have a 720 crank.
    ducatis have either a 90 degree or 360 degree crank depending on model.
    ducatis will "knock" if the idle speed is set too low or the TB's are out of synch.
    XB's will never "knock" unless there's something wrong internally.
    It's like a brief, barely audible slap on acceleration from stand still. It was louder before I tightened the chain, but even then it was only audible on acceleration from stand still.



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