Chain knock and rattle F800GS '16

Discussion in 'Parallel Universe' started by Scarfall, Feb 24, 2020.

  1. Scarfall

    Scarfall Adventurer

    Joined:
    Jan 22, 2020
    Oddometer:
    17
    Location:
    UK
    I got this bike recently at 6k miles and have done 4k on top. It only had one owner before and never had chain and sprocket changed.

    A month ago I noticed a chain rattle when pulling from first gear that goes away when I tighten it to the tight side of the slack range. BMW says leave the chain slack between 35mm and 45mm. The slack went away when I set it to 35mm.

    I then noticed a quick wear of the chain and now it rattles even at 35mm. The chain is still within it's recommended 144mm (across 10 links). My front sprocket is looking a bit worn so I tried to fit another one to see if that was the problem. I still intend to replace both sprockets' and chain in a couple of weeks. All the links move freely and none are seized.

    With the chain out of the way and the sprocket bolt removed, it is supposed to slide right off. But it is stuck. It looks like it fused with the countershaft spindle.

    I have tried soaking it with penetrating oil with multiple applications for over a week. Tried hammering it, tried to dilate the sprocket with a blowtorch even. I tried a gear puller but it still won't budge!

    [Here is a photo](https://i.imgur.com/cZvt4ty.jpg) of how it looks.

    [Here is a video]() of the rattle. And [here in slow motion](), with the knock happening at 00:32s.

    I don't want to get a new chain and sprocket set until I can get the old sprocket off. Until then, what is causing this knock and rattle?
    #1
  2. SnoDrtRider

    SnoDrtRider I've been lost here before...

    Joined:
    Mar 21, 2006
    Oddometer:
    6,881
    Location:
    South Jersey... Close to the Pines
    Chain adjuster blocks look like they have reached their limits?
    Also looks as if the rear sprocket is pretty well worn. A good photo of the sprocket test would be good to verify this. once the teeth get hooked they make the chain jump around as shown in the video so that is what I assume is going on.

    It is also possible the rear wheel bearings are bad.... drop the chain off the rear sprocket and check for play in the bearings as well as the sprocket carrier bearings (There are two wheel bearings and one sprocket carrier bearing).
    #2
    Benduro likes this.
  3. FredRydr

    FredRydr Danger: Keep Back 300 Ft.

    Joined:
    Aug 16, 2005
    Oddometer:
    4,097
    Location:
    Carlisle Pennsylvania USA
    Binding links. Replace the chain. Do the sprockets while you're at it.
    #3
  4. bmwroadsterca

    bmwroadsterca RadioFlyer

    Joined:
    Jan 3, 2007
    Oddometer:
    972
    Location:
    Lanark County near Ottawa ON
    I have never seen a chain adjuster that far back! And you say the bike has 10K miles?
    #4
  5. bmwroadsterca

    bmwroadsterca RadioFlyer

    Joined:
    Jan 3, 2007
    Oddometer:
    972
    Location:
    Lanark County near Ottawa ON
    Also perhaps it's just an illusion but it looks like there is an extra piece in front of the chain adjuster block? Why am I thinking that this isn't the stock chain but a longer one?
    Chain adjuster 2.jpg
    #5
    FredRydr likes this.
  6. FredRydr

    FredRydr Danger: Keep Back 300 Ft.

    Joined:
    Aug 16, 2005
    Oddometer:
    4,097
    Location:
    Carlisle Pennsylvania USA
    Imagine the excitement when it vibrates out!
    #6
    cgguy09 likes this.
  7. SnoDrtRider

    SnoDrtRider I've been lost here before...

    Joined:
    Mar 21, 2006
    Oddometer:
    6,881
    Location:
    South Jersey... Close to the Pines
    Something doesn't add up...
    Bike has 10,000 miles and either the chain has stretched a LOT or the chain has already been replaced by a longer one. I changed my chain at around 25,000 miles which IIRC is about what most people report getting on the original chain.

    Could be the PO kept the chain way too tight and caused excess stretch? But the poster says the link to link measurement is in spec?
    #7
  8. B_C_Ries

    B_C_Ries Long timer

    Joined:
    Mar 15, 2013
    Oddometer:
    10,973
    Location:
    Imperial Valley, California
    If a chain starts to go out of adjustment quickly you really need to replace it as soon as possible.
    #8
  9. dirtfarmerrich

    dirtfarmerrich Richard Supporter

    Joined:
    Dec 20, 2008
    Oddometer:
    188
    Location:
    central Illinois
    It’s probably the wheel bearings.
    #9
    SnoDrtRider likes this.
  10. BMW-K

    BMW-K F800GS FTW!

    Joined:
    Nov 11, 2004
    Oddometer:
    2,942
    Location:
    Anaheim, CA
  11. morfic

    morfic Been here awhile

    Joined:
    Jul 31, 2017
    Oddometer:
    669
    Location:
    San Antonio
    That’s one ugly front sprocket.

    When my chain went from adjusting once in a while to every week I tossed it and it was almost as long as the Out of box, unshortened 120 link chain I replaced it with and I was no where near the limit of the adjuster.

    Figure out how to get the sprocket off and replace both sprockets and the chain, that’s a gnarly looking set and setup.
    #11
  12. woodsguy

    woodsguy KTM Aficionado

    Joined:
    May 25, 2008
    Oddometer:
    143
    Location:
    Huntsville, Tx
    On my 2016 as the chain wore, he got some chatter, probably trying to ride up on sprockets. At that time, it's time for a new set.
    #12
  13. bakercdb

    bakercdb Still searching

    Joined:
    Nov 28, 2014
    Oddometer:
    272
    Location:
    In flux
    I was riding my 15 F800GSA in Africa and had to wait to replace a 24k mile plus chain/sprockets.
    The chain started to "slap" around like it was far out of adjustment (chain and rear sprocket weren't all that bad yet).
    But, the front sprocket had worn a lot and was hooked enough to grab the chain and create unusual slapping.

    What's the front sprocket look like?
    #13
    rjmorel likes this.