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fork oil level/volume for xj 650 rj

Discussion in 'XJ Technical Chat' started by kosel, May 18, 2019.

  1. kosel

    kosel Active Member Premium Member

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    I've just re-built the forks using XJ4Ever's Performance Fork Rebuild Kit and I'm not sure what the right amount of fork oil (by volume or level) I need.

    From XJ4Ever: "1982 XJ650RJ Seca: 236cc or 7.98 fluid ounces. 10W fork oil. Fork oil level is specified as 400mm (15.75") below the top of the tube without the spring installed, forks fully collapsed." This matches the owner's manual.

    XJ4Ever adds, "...the above fork oil volumes are for use only when using the stock fork springs. The use of aftermarket performance front fork coil springs will change those volumes....A better way to determine the amount of fork oil that is needed and necessary is via the measurement of the fork oil level within the tubes...in any case, if using aftermarket springs, the factory oil level recommendation is not always useful"

    Making me more unsure, the oil level (400mm below...) is dramatically different than for the 650 Seca Turbo (180mm), despite their having almost the same oil volume (236cc vs. 238cc).

    As always, your experience and input is appreciated!
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    if you add 236cc or 7.98 fluid ounces. 10W fork oil. (or whatever grade you desire) you will be good. you could measure the height too but why would you if you can just pour the oil.
    rounding to 8 oz is ok

    if you used aftermarket springs then you would do the dip stick measure
     
  3. k-moe

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

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    The Seca Turbo is a heavier bike and has different springs in the forks, which is why the oil level is higher. The springs take up more internal volume, leaving less for the oil.
     
  4. kosel

    kosel Active Member Premium Member

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    Unless I'm missing something, the dipstick method calls for no springs, so the result would be the same.
     
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  5. kosel

    kosel Active Member Premium Member

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    I wanted to provide some details, should anyone else need direction.

    I'm a big guy and the old springs were soft. The front end would really dive down when braking hard. I installed XJ4Ever's PERFORMANCE FORK REBUILD KIT (HCP20616). I have added 235 CC (not the 236 factory spec) because these new springs are made of thicker material (see image) and I prefer to make small changes. I used Bel-Ray 15W fork oil.

    The front is much tighter. I'm not sure yet if it's tighter than I want or if it just feels that way in contrast to how soft it was. I'll add any future oil weight or quantity adjustments to this thread.
     

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