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Thread: 2011 RT Adjustable Rocker Arms?

  1. #1
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    2011 RT Adjustable Rocker Arms?

    I am looking for adjustable rocker arms to simplify valve lash adjustment. Any one know of a source. I think changing the oil cups is ridiculous to adjust valve lash. Not like I have a parts warehouse available to try different oil cups to acieve the desired lash. Dumb design in my opinion. Aren't the older designs equipped with factory adjustable rocker arms?

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    Ponch ponch1's Avatar
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    Anecdotally, the shims seem to hold their adjustment longer. I'd rather have shims than the screw adjusters, but that is me. Actually, if they came out with hydraulic lifters, that would be even better.
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    Rally Rat
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    I waited a LONG time for BMW to make an overhead cam boxer. I now have one and love it. Everything should stay in tune for a long time.

    I checked the valves at 2700 miles. all 8 were right in the middle of the spec. Throttle bodies were in perfect sync at Idle. Bike has no glitches.

    Some of this is the result of shims and buckets instead of rocker arms and pushrods.

    I will just change the oil every 3,000 miles for the next 10,000 and check things again. So far it keeps running better. It has a LOT more low end and midrange than my oilhead. Smoother too

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    Long Range Rifleman
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    Quote Originally Posted by Ponch1 View Post
    Actually, if they came out with hydraulic lifters, that would be even better.
    Concur.

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    Cam Killer marchyman's Avatar
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    Quote Originally Posted by Inga2011 View Post
    Not like I have a parts warehouse available to try different oil cups to acieve the desired lash.
    You don't (or at least shouldn't) adjust valves with the semi-sphere shims by trial and error. The shims come in fixed sizes from 4.60 ~ 5.70 mm in .05mm steps.. Measure the current value. If not within range pull the shim and read (or measure) the current size. You now have all the information needed to calculate and order the appropriate shim.

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    If I increase the shim size by .10mm I doubt it would decrease the valve lash by the same amount, given the geometry, so I am skeptical it's that simple, that is why I said trial and error. Good to know the info you gave though. Still looking for adjustable rocker arms, been wrenching on race cars with solid camshafts my whole life and it's a quick and simple adjustment. I think BMW was looking to save a few nickels and turned a few minutes work into disassembling and reassembling of the rocker set up.

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    Sometimes it's best to read the manual

    Dude Just follow the factory instructions for valve adjustment. It will work. Sometimes too much thinking gets in the way of doing a job proper. Shim valve adjustment has been used for high performance OHC units forever. Shims only go out of spec with wear, no lock nut to loosen allowing adjuster to change. The BMW R overhead cam system is one of the simplest I've ever seen on a OHC motorcycle. Does require a little bit of math though. Do not reuse the retaining circlip!
    Will Stagg Central Coast of Commiefornia
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    Rocker arm

    You are not going to re-engineer the top end of that motor. Buy a low mile Hexhead and adjust valves to your hearts content. It is very simple I think.

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    Ponch ponch1's Avatar
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    Quote Originally Posted by wrenchbender View Post
    You are not going to re-engineer the top end of that motor. Buy a low mile Hexhead and adjust valves to your hearts content. It is very simple I think.
    Or learn to live with the shims.
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  10. #10
    Norm Norms 427's Avatar
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    1) I'm not familiar w adjustable rocker arms but I'd like to learn.

    2) I thought all the shims came in .05 mm increments too, until I found one in my motor that came from the factory that was a .025 increment. It has 5.425 stamped on the side.

    3) I paid about $120 to have some spare semi spheres on hand so I don't have to go to the dealer every time I adjust valves. I selected what appeared to be the likely sizes that I'd need, put them in a fishing tackle type plastic tray and labeled each little cube for size.

    4) I'm not technically savvy as to why camheads would stay in adjustment longer than the hexheads. Metal to metal wear is the issue whether it's semi spheres and rockers or pushrods and rockers. ?

    The camhead is the best valve adjustment design I've had on a m/cycle, but, maybe if we're lucky the next generation will have hydraulic valves.
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  11. #11
    neanderssance man sedanman's Avatar
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    With overhead cam valve train there are fewer metal to metal contact points than with a push rod style.

    OHC, rocker pivot, cam to rocker arm, rocker arm to valve tip (3)

    Push rods, cam to follower, follower to push rod, push rod to rocker arm, rocker arm pivot, rocker arm to valve tip. (5)

    Push rod style typically has threaded adjusters on the rocker tips, these can be more difficult to get perfect lash in the first place.

    Valves going out of adjustment don't always get loose from wear at these points, they are just as likely to get tight from the valve receding into the valve seat.
    Paul
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  12. #12
    na1g
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    I haven't had my covers off yet (only 9,000 miles) but I bet there isn't room in there for a screw+locknut adjuster anyway.

    But hydraulic valve adjusters? Now there's an idea whose time came a long time ago. For relatively low-revving motors like the boxer, hydraulic adjusters work just fine. I had (and wish I still had) a Honda Nighthawk 700 that had hydraulic valves and redlined over 10K. There is no reason why a touring bike shouldn't have these, in my opinion (which isn't worth much - just ask my wife)

    pete

  13. #13
    Registered User mneblett's Avatar
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    Quote Originally Posted by Norms 427 View Post
    4) I'm not technically savvy as to why camheads would stay in adjustment longer than the hexheads. Metal to metal wear is the issue whether it's semi spheres and rockers or pushrods and rockers.
    The shims are extremely hard (hard-faced? dunno). They have extremely low wear.

    My camhead RT's are holding adjustment better tham my oilheads/hexheads. Whether that is due to decreased valve train wear (I believe so), or better metalurgy and temperature control at the valve seats so they erode slower, I don't know. I do know that because they wear so slow, I will always be able to take a trip without worrying whether I'd need to adjust the valves in the middle of the trip.

    FWIW, I find the camhead valves easier to check, in part because access to the gap is good, and in part because you don't need three hands to simultaneously hold two feeler gauges on each pair of valves to avoid inaccurate adjustments.

    And if a shim does need to be replaced on a camhead, it could hardly be easier -- pull a clip, slide the follower out of the way, swap the shims.

    Not to mention the math is simple -- old shim thickness + gap - desired clearance tells you what the new shim thickness should be.

    I currently have airheads, oilheads and a camhead -- I'll take the camhead shim arrangements every time.
    Last edited by mneblett; 10-12-2012 at 06:57 PM.
    Mark Neblett
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  14. #14
    Ponch ponch1's Avatar
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    Quote Originally Posted by na1g View Post
    I haven't had my covers off yet (only 9,000 miles) but I bet there isn't room in there for a screw+locknut adjuster anyway.

    But hydraulic valve adjusters? Now there's an idea whose time came a long time ago. For relatively low-revving motors like the boxer, hydraulic adjusters work just fine. I had (and wish I still had) a Honda Nighthawk 700 that had hydraulic valves and redlined over 10K. There is no reason why a touring bike shouldn't have these, in my opinion (which isn't worth much - just ask my wife)

    pete
    If they put in hydraulic lifters it would be one less thing the dealers can service. The next boxer has a wet clutch and throttle by wire. I believe the clutch is in the front of the engine and with TbW, there's no throttle sync needed anymore. If they put in hydraulic lifters, all the maintenance there would be are fluid changes. Most people can do that and now with the engine and transmission sharing the oil, there's one less fluid change, although with antifreeze, there's one more, but it wouldn't be often, depending on the type of coolant.
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  15. #15
    Ponch ponch1's Avatar
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    Quote Originally Posted by sedanman View Post
    With overhead cam valve train there are fewer metal to metal contact points than with a push rod style.

    OHC, rocker pivot, cam to rocker arm, rocker arm to valve tip (3)

    Push rods, cam to follower, follower to push rod, push rod to rocker arm, rocker arm pivot, rocker arm to valve tip. (5)

    Push rod style typically has threaded adjusters on the rocker tips, these can be more difficult to get perfect lash in the first place.

    Valves going out of adjustment don't always get loose from wear at these points, they are just as likely to get tight from the valve receding into the valve seat.
    So far with two adjustments done, the valves have always been loose, worse on the clutch side both times. Go figure.
    My Motorrad
    BMWMOA 162849 | BMWRA 41335 | VROC 8109-R | VBA 19

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