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Primary Chain Yamaha XJ 900f

Discussion in 'XJ Technical Chat' started by Franz, Apr 8, 2018.

  1. Franz

    Franz Active Member

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    I was wondering what mileages owners had to change their primary drive chain on the XJ 900f? What are the signs of a worn chain thanks?
     
  2. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    Never.
    It isn't a primary chain. The HYVO chain only spins the alternator, and allows the starter to turn the engine over.
    IIRC the chain is (was?) rated by the chain manufacturer to be good for 150,000 miles, but will likely last longer since it has almost no load placed on it.
     
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  3. Franz

    Franz Active Member

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    Thanks k-moe here was me thinking it was like my old Honda CB 750 SOHC, how did I manage that? I didn't realize it just drove the alternator etc, I got nothing to be concerned about and that's great.
     
  4. Franz

    Franz Active Member

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    Sometimes k-moe I hear a noise from my engine and I thought it was the aforementioned chain, mabe it is the gearbox but the bike runs perfectly and I have no problems selecting gears and it is not slipping out of gear during acceleration. I know diagnosis of impossible when you cannot hear the bike but do you have any ideas on this thanks?
     
  5. Franz

    Franz Active Member

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    .

    So I assume k-moe the large gear on the right of this XJ 900f crankshaft is the primary drive which meshes with a gear on the clutch basket. Are the other two in the middle of the crankshaft for the timing chain and the oil pump drive? XJ 900f Crankshaft.jpg
     
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  6. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    The large gear on the right is the primary drive gear.
    The small sprocket in the center is for the cam chain.
    The larger sprocket at left-center is for the alternator/starter clutch HYVO chain.
    The oil pump is driven off of the clutch input shaft (the one that is driven by the primary drive).
     
  7. Franz

    Franz Active Member

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    Cheers k_moe l understand now.
     
  8. cds1984

    cds1984 Active Member

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    A good indicator is the oil spray nozzle being ground down by the primary drive chain slapping against it.
    You can pull it out and give it a look without splitting the engine by taking off the gear lever cover and remove the bearing cover where it is located behind... i think... from memory.
     
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  9. Franz

    Franz Active Member

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    Good to know the oil spray nozzle can be checked this way cheers cds1984.
     
  10. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    The oil jet is behind the alternator bearing housing. The alternator rotor has to be removed to get at it, so it's not so simple to check.
    The oil nozzle is in no danger unless the alternator chain guide has failed, and that is where pulling the shift cover comes into play. There is a large oil passage under that cover that lets you peek into the transmission and check for broken bits of the guide.
     
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  11. cds1984

    cds1984 Active Member

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    Aah now I remember where it is! oops.
    Still good indicator I reckon. Although I do like to split engines for the hell of it, it seems.
     
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