LC4 rocker arms

Discussion in 'Thumpers' started by matsplatuk, Nov 1, 2005.

  1. matsplatuk

    matsplatuk Adventurer

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    During my firts valve clearance check (Thanks Creeper for your exelent guide) i noticed that the inlet rocker arm moved laterally along its shaft. This didn't seem to heppen with the exhaust rocker arm 'till i took the upper cylinder head assembaly off. Now they both move about 1mm side to side on their shafts. Is this OK?

    I did a search but only found one mention of inlet rocker arms failing on older machines but that was it. Does anyone know more on this?

    Thanks, in advance - Mat

    [​IMG]
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  2. Loadedagain

    Loadedagain making chips

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    whoa.... now i see why that bearing needs replacing at regular interval... it's flippin tiny!
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  3. creeper

    creeper Still alive...

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    Using your photo as a reference, see the shims on the drive side of the cover? KTM recommends those to be 1.00mm thick to establish rocker arm position.
    Then you fill the gap on the spark plug side with shims to obtain an end clearance of 0.20mm to 0.030mm.

    Shims are available in 0.015, 0.030, 0.050 and 1.00mm.

    C
    #3
  4. Loadedagain

    Loadedagain making chips

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    ps... rockers should float on the shafts. i'm not sure of allowable end play, but 1mm doesn't seem too bad. i'll have a peek in the manual for a spec... betcha creeper beats me to it though.
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  5. Loadedagain

    Loadedagain making chips

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    told ya....
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  6. creeper

    creeper Still alive...

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    Just did one a few days ago... :ksteve
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  7. matsplatuk

    matsplatuk Adventurer

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    Oh OK, i think i understand,

    I leave the 1mm shim on the cam chain side but then add shims to the spark plug side so the total play/gap on the shaft is 0.2 - 0.3mm?

    Is this something worth doing or will it be safe to leave it till another day?

    I suppose i just go to a dealer and ask for LC4 rocker shaft shims?

    Funny that this procedure isn't mentioned in the LC4 motor manual ive got.

    Many Thanks Guys - Mat
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  8. creeper

    creeper Still alive...

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    Right out of the book...

    Considering 1.0mm is over three times what KTM recommends as a maximum end play, you should probably take care of it now.
    It's not just end play, but potential acceleration and deceleration of the rocker arm laterally. The more play, the greater those forces, the greater those forces the more thrust and wear they can generate.
    At least that's the viewpoint I would take.

    C
    #8
  9. matsplatuk

    matsplatuk Adventurer

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    Thanks Creeper, ive now found the page in the service manual.
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  10. Tseta

    Tseta Lost

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    Hello,

    First of all, I'm sorry for digging up such an old thread. However, I searched the site and the Index Threads, and this thread is very closely related to my current issue.

    As I was checking the valve clearances (valve lash?) on my 2003 LC4 Adventure, I discovered that the exhaust side rockers had about 0.7mm of axial clearance, while the intake side rockers were right on (based on the information in this thread, at least...) at 0.3mm. (The bike currently has approximately 18tkm on it, but as I just recently acquired it, I have no further knowledge of previous usage or maintenance.)

    Even though Creeper already wrote a few words on the importance of having the correct axial clearance on the rockers, I am still slightly confused as to exactly what harm will the excess clearance cause?

    In addition, I am hoping that some of the more knowledgeable folks could chime in on this thread, specifically on how to actually adjust the clearance on the rocker arms. It is my current understanding that the process is quite tedious, involving taking the engine out of the frame. There seems to be minimal room to even perform simple valve clearance inspections and adjustments with the engine in the frame.

    So, should I start reading/translating the Indexed engine removal guide in preparation for the clearance adjustment or just relax about the whole issue and deal with it "later"?

    Thanks,

    Tseta
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  11. gunnerbuck

    gunnerbuck Island Hopper

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    Tseta,
    You do not need to remove the engine to shim out too much rocker play.... You need only to remove the valve cover and these instructions will help guide you: http://www.advrider.com/forums/showthread.php?t=112127 The shafts and rockers are contained within this cover so it is easy to work on...


    With the cover off, the rocker shaft will then slide out as the cover mounting bolts are what hold them in place.... What you will need is a selection of the shims so you can swap them out to obtain the correct play...

    Good luck...
    David..
    #11
  12. wrk2surf

    wrk2surf on the gas or brakes

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    3 years ago I actually lost or wore one out and half of it ended up in the clutch cover bearing near the front that lead to the starter not working correctly for months I chased this problem.... so I would say to always have those shims right on.
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  13. Tseta

    Tseta Lost

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    Thanks to gunnerbuck and wrk2surf for their insight on this issue, and of course to Creeper for his excellent rocker cover sealing guide. With these and various other bits of information, I adjusted the axial clearance of the exhaust side rockers by adding a 0.5mm thick shim. Now the clearance is spot on.

    Cheers,

    Tseta
    #13
  14. gunnerbuck

    gunnerbuck Island Hopper

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    Thank you for letting us know that things worked out....

    David...
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  15. creeper

    creeper Still alive...

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    "Spot on" is always good. :wink:

    C
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  16. JSL

    JSL Adventurer

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    I've had some issues with the rocker arm bearings (replaced the intake side bearing twice now) and I had about 1mm axial play. The guys from Sommer told me not to worry about it and that it is normal to have that much play.

    I did shim it anyway though.
    #16
  17. todd83-900t

    todd83-900t Been here awhile

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    What's the proper technique for measuring the axial play in the rocker arms? When I insert a feeler gauge between the thrust shim and the rocker arm the main shaft moves slightly, screwing up my measurement. The shafts are held in place with the long bolts but there is some slop in the shaft bolt holes.

    Should you just place the chrome end of the shaft perfectly flush with the cam shaft cover, with a straight edge, and then measure?
    #17
  18. Tseta

    Tseta Lost

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    I wrote the following to a fellow ADVRider in a related discussion:

    It is important to remember that the location of the rocker arm shafts and the rockers themselves is determined (mostly) by the two bolts that also in part hold the cylinder head top section in place. When you have taken the cylinder head top section off, there is no indexing of the rockers anymore by these bolts. You could, of course, temporarily insert the bolts trough the removed top section to line the rockers and shafts up correctly, but I feel that this has a greater chance for error. For this reason, I have always measured the rocker arm play while the cylinder head top section is fully assembled. Of course you cannot use the feeler gauge method in this case, but a dial indicator or even a vernier gauge works fine for measuring. Remember, you are looking for the amount of play, not an exact length measurement or such, so any two surfaces will do for measuring points. I use a vernier caliper's "depth" feature, measuring on the valve clearance adjusting nut, with the caliper body held against the edge of the valve inspection cover.

    Cheers,

    Tseta
    #18
  19. todd83-900t

    todd83-900t Been here awhile

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    Thanks!

    That little kibble of information is not in the engine manual!
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  20. ontherock

    ontherock ne'er do well

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    Thanks loads guys, great thread, I mixed up my shims when replacing rollers and this clarifies the murkiness and then some. Where can one find the repair manual?
    #20