South Wales Trail Riders

    Front sprocket play

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    crm250dude

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    Front sprocket play

    Post by crm250dude on Wed Oct 07, 2015 8:20 pm

    Took GaGa up Dr Petes tonight for some TLC - going to change back wheel bearings and stuff because of this annoying rattle / grind

    we noticed a bit of play on the sprocket shaft - in/out about 5mm or so - is this usual?

    its not the sprocket or the sprocket bolt /washer - as they are both new - its the actual shaft

    any suggestions?

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    phil990

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    Re: Front sprocket play

    Post by phil990 on Wed Oct 07, 2015 8:27 pm

    Not good Suspect
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    wolfy

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    Re: Front sprocket play

    Post by wolfy on Wed Oct 07, 2015 8:32 pm

    Eh... scratch Dr Pete had no answer Snigger
    No idea mate Google it....

    curl666

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    Re: Front sprocket play

    Post by curl666 on Wed Oct 07, 2015 8:51 pm

    Play on the sprocket shaft can be caused by incorrect chain tension. The chain would of been run too tight for a long period.

    I'm not familiar with the design of the crm engine but on some bikes it can be a relatively easy fix, usually a series of bolts around the shaft, remove the shaft and install a new bearing.

    However some bikes you will have to totally strip the engine/gearbox to be able to replace it.

    It's quite a common issue on the Honda transalp and Africa twin. Both bikes require an engine rebuild to replace shaft bearing.
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    mizzed

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    Re: Front sprocket play

    Post by mizzed on Wed Oct 07, 2015 8:51 pm

    Just measured the end play with digital calipers, and its coming out around 1.05mm.

    Cant find any end play figures in ktm manuals, but googling it comes to 0.1-0.3mm is acceptable, and would be consistant with the end play on my 12 450, but this is a different generation motor, so cant really compare.

    there is 0mm side to side play.

    is there anyone with a RFS motor that could check what endplay they have or know what the upper tolerance would be?
    And would this be a worn spacer? Cant see it but worth checking,


    More worrying is that I just dropped the oil and am seeing this ammount of metal on the magnet after circa 300miles since last service.

    [You must be registered and logged in to see this image.]

    I know mine gets a few little bits, but nothing like that, but again a different gen motor, either way I'm getting the definate feeling the motor needs a teardown :/
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    crm250dude

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    Re: Front sprocket play

    Post by crm250dude on Wed Oct 07, 2015 8:53 pm

    curl666 wrote:Play on the sprocket shaft can be caused by incorrect chain tension. The chain would of been run too tight for a long period.

    I'm not familiar with the design of the crm engine but on some bikes it can be a relatively easy fix, usually a series of bolts around the shaft, remove the shaft and install a new bearing.

    However some bikes you will have to totally strip the engine/gearbox to be able to replace it.

    It's quite a common issue on the Honda transalp and Africa twin. Both bikes require an engine rebuild to replace shaft bearing.

    sorry - i should have said its on my KTM 450 exc '04 RFS engine
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    crm250dude

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    Re: Front sprocket play

    Post by crm250dude on Wed Oct 07, 2015 8:53 pm

    and the chain has been run a bit tight recently i fear

    curl666

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    Re: Front sprocket play

    Post by curl666 on Wed Oct 07, 2015 9:03 pm

    I've got a Ktm 450 exc in the garage. I can inspect the front sprocket shaft on Thursday or Friday evening, if you don't have an answer by then.

    I've owned a 2003 450 exc rfs and a 2005 400 exc rfs both bikes would have a grey metallic sludge on the drain plug. I'd usually service every 10 hours.
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    mizzed

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    Re: Front sprocket play

    Post by mizzed on Wed Oct 07, 2015 9:04 pm

    curl666 wrote:I've got a Ktm 450 exc in the garage. I can inspect the front sprocket shaft on Thursday or Friday evening, if you don't have an answer by then.

    I've owned a 2003 450 exc rfs and a 2005 400 exc rfs both bikes would have a grey metallic sludge on the drain plug. I'd usually service every 10 hours.

    Sound thanks, would be a great help.

    Do you get metal shards like that and to that amount after 10 hours on yours?

    curl666

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    Re: Front sprocket play

    Post by curl666 on Wed Oct 07, 2015 9:08 pm

    crm250dude wrote:and the chain has been run a bit tight recently i fear

    Since mizzed has updated with a bit more info, a tight chain would affect side to side play on the shaft.
    He states you have zero side to side play. So less of a worry in my opinion.

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