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Thread: r1250 timing belt

  1. #1

    r1250 timing belt

    I read that the new engine will have a toothed belt instead of the one currently used. I hope someone smarter than me can help.does the new design weigh less and cause less parasitic power loss? Or is the new belt quieter? Or is the new belt cheaper? And i sure hope the answer to this question is NO.Will the the toothed belt last longer and not need to be replaced. I have alot of miles on my 2015 RT and am hoping I never need to have it's timing chain replaced.I am positive someone out there will know the answers to my questions . Thanks in advance for your insight.

  2. #2
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    Quote Originally Posted by jimbem View Post
    I read that the new engine will have a toothed belt instead of the one currently used.
    Everything I see shows a chain to drive the cams.

    1:33 into this video shows the cams with the chain.

    https://www.youtube.com/watch?v=ivXBBa5XtKo

  3. #3
    got, got, got no time... rguy's Avatar
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    I presume it is this type of chain
    http://chain-guide.com/applications/...oth-chain.html

    Vs the previous roller type chain.
    https://goo.gl/images/5tPCX2

    The toothed chain should be a lot quieter.
    Neal - '16 R1200GS / '81 R65
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  4. #4
    Quote Originally Posted by rguy View Post
    I presume it is this type of chain
    http://chain-guide.com/applications/...oth-chain.html

    Vs the previous roller type chain.
    https://goo.gl/images/5tPCX2

    The toothed chain should be a lot quieter.
    The video referenced in the above post #2 does indeed show an inverted tooth chain or whatever it is called. It is not a normal roller chain. And it is not a belt.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  5. #5
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    Hi

    It's called a hi vo chain I believe.
    Later,
    Norm

  6. #6
    you guys are right . i mispoke .It is a toothed chain ,not a toothed belt. But that still doesn't answer my questions.What exactly are the benefits to the new style chain? Or did BMW make the change only to cut costs?

  7. #7
    reading then info Paul supplied it sounds like the change was made to make the motor quieter. Which chain should we expect to last longer though?

  8. #8
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    Good question.
    Hi-vo chains are typical in automotive engines and Japanese brands, roller chains are not the norm. On the other hand Harley used Hi-vo chains in the early Twin Cams and in 2006-2007 went to roller chain for the cam drive.

  9. #9
    Some good info on cam chain types...

    https://www.hemmings.com/magazine/hc...g/1281485.html
    Lee A. Dickinson - Danielsville, GA USA
    Airheads #3480 | Iron Butt Assn. #8914
    1992 R100RS - 1993 K1100RS - 2013 R1200GS

  10. #10
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    Quieter

    Quote Originally Posted by jimbem View Post
    reading then info Paul supplied it sounds like the change was made to make the motor quieter. Which chain should we expect to last longer though?
    I'm not an expert, but I understand that the EU now has regulations limiting the operating sound levels of all motor vehicles (including motorcycles). This is not a "noisy exhaust" issue, they require the engine noise, tire noise, etc. to add up to no more than some set level of noise. Various motorcycle manufacturers are making changes to their engine designs, etc to meet the regulations. I believe KTM changed their valvetrain on some of their bikes to meet the regulation. I presume BMW has to do the same.

    I expect that the new chain is more expensive, but quieter - I doubt if it is much different in expected lifetime, but maybe we'll be pleasantly surprised.
    Bob
    2014 R1200RT

  11. #11
    There is no reason that I can discern why a cam chain should limit the life of an engine. If a cam chain can't outlast the valves and the rings it would be a mechanical travesty.
    Last edited by PGlaves; 10-22-2018 at 03:14 PM.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  12. #12
    Quote Originally Posted by PGlaves View Post
    on that I can discern There is no reason that I can discern why a cam chain should limit the life of an engine. If a cam chain can't outlast the valves and the rings it would be a mechanical travesty.
    Which puts all airheads in that category. I have historically gotten 80K miles from heads, but by 50K miles the timing chain is eating its tensioner pad and introducing spark scatter. I'd point out that I am not a "run to failure" type of person. Airhead heads often fail by popping the head off an exhaust valve (with the obvious internal consequences). Trying to time your repair one day ahead of that event is like counting on a deathbed conversion to keep you out of hell.
    Lee A. Dickinson - Danielsville, GA USA
    Airheads #3480 | Iron Butt Assn. #8914
    1992 R100RS - 1993 K1100RS - 2013 R1200GS

  13. #13
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    cam chains

    hivo cam chains run quieter and stretch less than conventional cam chains. Cam chain stretch retards cam timing from original specs. Not a big problem, typically cam chain tensioners give more problems than cam chains.

  14. #14
    If a chain running in a well lubricated sealed chamber wears significantly then it is made of inferior materials. I took the oil/water pump and cam chain case off the front of my K75 to check for cam chain and tensioner wear twice. Once at about 60,000 miles and once at about 150,000 miles. Detecting no significant wear I ignored it until the bike was totalled at 370,000 miles. But classic K bikes are not Airheads.
    Paul Glaves - "Big Bend", Texas U.S.A
    "The greatest challenge to any thinker is stating the problem in a way that will allow a solution." - Bertrand Russell
    http://web.bigbend.net/~glaves/

  15. #15

    timing chains

    When I was a young auto mechanic in the 60's 70's, replacing a timing chain was a very common repair, often after jumping the sprockets.

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