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Info CBF chain tension

Discussion in 'Maintenance' started by hikerrobot, Aug 22, 2016.

  1. hikerrobot

    hikerrobot Active Member

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    Hi all,
    Wondered if anyone else, particularly with same bike :), finds it hard to get the chain tension correct on a CBF 250? When I bought the bike it was so slack it was a joke. I have since tightened it to the correct tension, but the chain slaps when at low revs. I take this to be an indication that the tension is not great enough. Any comments, thoughts gratefully received. :)
     
  2. Linkin

    Linkin The Apprentice Premium Member Dirty Wheel Club Contributing Member

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    Chain is worn out and you need a new one. Best to change the sprockets too.
     
  3. my67xr

    my67xr Bike Enthusiast Staff Member Premium Member Contributing Member

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    When you adjust the chain, have someone sit on the bike while you do it.
    With most swingarm's they act like a lever, pivoting off the front mounting bolt.
    As the rear suspension compress's the rear axle move's further away from the front sprocket.
    So the chain need's to be adjusted so at it's longest point there is still a bit of movement up and down.
    The longest point is where the centre of the front sprocket, the swingarm front mounting bolt and the centre of the rear sprocket are all lined up
    So when you tension your chain you need to allow for this movement

    If you don't have any movement when the centre's are all lined up then the chain will stretch, and can also cause problem's like prematurely wearing the output shaft bearing behind the front sprocket, it can chew out rubber's/buffer's inside your rear sprocket hub if it has cush drive, and wear out the chain slider on the front of the swingarm too.

    Check you chain slider is in good condition

    If you replace your chain, use a good quality one like a H/D DID or similar, cheaper chain's will stretch quickly
    And lube it up with some decent chain lube, the grease that's on a new chain isn't enough, it's basically there to stop it rusting while it's in the box


    If you remove your chain you can check how worn it is by seeing how much it curve's when layed out
    Also if you hold one of the link's at the back of your rear sprocket and pull it away from the sprocket it should hardly move, if it does move a bit then i'd say your chain is stretched.

    If the teeth on your sprocket's are worn i would replace them.
    You will notice that the point's of the teeth are no longer flat, they will be sort of sharp (see pic below)

    [​IMG]

    Worn out chain

    [​IMG]

    New sprocket at the front, worn sprocket at the rear

    [​IMG]
     
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  4. hikerrobot

    hikerrobot Active Member

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    Thanks for your reply. I should perhaps have added more info. The bikes has only done around 1500 on current chain. The chain is nowhere near the wear markers and the teeth are nice and wide, not like the sharp teeth on the image above. So change of chain and sprockets is not necessary.
     
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  5. hikerrobot

    hikerrobot Active Member

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    Thanks for your excellent reply, very informative. Found it useful about the longest point of travel.
     
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