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900rk 2nd gear kachunk

Discussion in 'XJ Technical Chat' started by to the max, Nov 18, 2021.

  1. to the max

    to the max Member

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    took the 900 for it's first ride today since i got it a couple months ago

    sit rep...

    it shifts through the gears fine with low torque on them. when i gave it a small portion of "the beans" in 2nd gear, i feel a serious (what i would describe as) "kachunk".... it does then continue to go.

    when i did the oil change on it when i first got it there were small particles of metal the oil filter housing.

    what's my next step?
     
  2. jayrodoh

    jayrodoh YimYam Premium Member

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    There is a spring loaded cam in the middle gear that will absorb any shock from applying power to the rear wheel. Parts 4 and 5 in the diagram below is probably what you are hearing, they slip and compress the spring to absorb the shock, then they "pop" back into their normal position until loaded up again. My 650's do it too when you hit the gas hard or pop off the line. It's a little unsettling the first time you hear/feel it but it is normal.

    Change the oil and check again for shavings after 1000 miles or so.

    Middle Gear.png
     
    Last edited: Nov 19, 2021
    Franz likes this.
  3. Franz

    Franz Well-Known Member

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    My 900 does the same. Hope it's not plastic from the starter chain guide in your oil filter?
     
  4. Minimutly

    Minimutly Well-Known Member

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    “A small portion of the beans” - I wouldn’t expect this to lift the middle gear pawl off its seat. More likely, I suspect is the second gear dogs have rounded... bugger.
    Needs looking into, but if this doesn’t happen in 1st gear, with “a large portion of beans” then I’m right, and it’s a gearbox rebuild.
     
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  5. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Actually, the XJ900 models DO use the rubber cushions within the rear wheel "hub clutch", just like the chain drive bikes do.......
     
  6. jayrodoh

    jayrodoh YimYam Premium Member

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    Yup, you are correct. I knew the motor did so I figured they wouldn’t have done both. Shoulda looked before I posted!
     
  7. Minimutly

    Minimutly Well-Known Member

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    That's a big assumption, myself I would say they probably kept the spring and pawl as well - on the basis that it was there in the trans anyway, but that's an equally big assumption, having never stripped a 900...They do function quite differently...
    Someone must know?
     
  8. jayrodoh

    jayrodoh YimYam Premium Member

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    Yup, that's on me. Should've checked and even had the resources to do so. Edited my original post to remove bad info.

    Goes back to what you said here, if happens in one gear only under light throttle then I suspect you're on point. I know mine will do it in multiple gears and with heavy throttle application so I'm not concerned.

    @to the max Curious to see what you find out
     

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