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Info ZXR 250 fork seal/oil change (basic tools)

Discussion in 'Kawasaki 250cc In-line 4's' started by sharky, Feb 13, 2019 at 4:34 PM.

  1. sharky

    sharky Well-Known Member Premium Member

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    This is to take the mystery out of doing your own fork seals without the special tools. This is for the "c" model forks, the "a" model,I think, has a different spring & spacer setup.
    These are the tools that will get you by- a shifting spanner, a 12,14 & 17mm spanner, a sm & med flat blade screwdriver, sm & med long nose pliers, a syringe with 85mm of hose, a roll of electrical tape, silicone grease(optional) & an old fork seal with a cutout section just wide enough to squeeze over the fork.

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    First off be sure to crack the top plug before removing the forks.

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    With the forks now removed,unscrew the top plug from the fork outers, now pull up the top plug while pushing down on the spacer, wedge the spacer under the piston rod nut.

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    Now with the med screwdriver wedge the spacer & nut apart & squeeze in the 12mm spanner under the nut.

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    Place the 14mm spanner on the rod nut & the 17mm spanner on the top plug, crack & unscrew by hand,remove spanners.

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    Remove damping rod,spacer,guide & fork spring.

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    Drain the oil, then at a 45° angle, pull the piston rod in & out to drain the cylinder, place in a dry container to drain further & start on the next fork.

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    Remove the dust seal & retaining ring.

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    Now the forks are ready for disassembly, hold the fork horizontal & pull apart until you feel them stop, then give them a few crisp snaps back & forth until they seperat, remove- bushes,washer,oil & dust seal.

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    The forks are now ready for a clean before re-installing the gear, at this point I like to remove the cylinder also for easier cleaning(optional). You will need a few more tools for this, if you wish to do so you will need a 10mm Allen key, a breaker bar to fit over the allen key, for the fork cylinder I use a 16/18mm double ended plug spanner, 18mm for the fork cylinder & another spanner fits the 16mm end to lengthen, hold the cylinder end tight & crack the allen bolt, I do it in the vice but can be layed flat on the ground with a foot on the fork lower, you may need another person to help.

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    Forks are clean, now the bushes & seals need re-assembling. Use a plastic bag smeared in fork oil or silicone to slide the oil & dust seals over the sharp edges,pop the bag & pull down through the seal to remove. Install the parts in the correct order the right way up- dust seal first then oil seal, washer,outer bushing, inner bushing, the retaining ring can pop in later. MOST IMPORTANT- the washer has a flat & rounded side, the rounded side faces upward towards the outer bushing, the flat side of the washer sits flush against the oil seal.

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    Seperate the washer and outer bush from the seals & wrap electrical tape about 5mm thick in the middle of the tube.

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    Sit the forks on the ground & give it half a dozen good whacks, check under the washer to see if the bush has bottomed out, remove tape.

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    Slide the new oil seal down now & re-tape, insert the cutout oil seal facing the same way as the new oil seal. Slowly push the seals down until the cutout seal is just inside the tube, then give it a few mediumish whacks, dig out the cutout seal & rotate 180° & go again, remove cutout seal & tape.

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    Insert the retaining ring & dust seal.

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    Fully compress the forks & watch out for the dust seals, hold the piston rod nut & fill with oil, pump the rod up & down slowly while keeping the oil above the holes.

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    Sit the syringe on the fork tops & remove oil until the recommended 85mm from the top.

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    Now some important bits before re-assembly.
    PISTO ROD NUT-manual states 12mm of visible thread, I screw it right down (13.5mm) which seems to allow a few more clicks adjustment in suspension, chamfered side of the nut faces downward.

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    FORK SPRING- smaller end of spring faces upward.

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    TOP PLUG- manual states a 25mm gap between the compression damper adjuster & where the damping rod inserts, turn the adjuster until 25mm is attained.

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    Unscrew the piston rod nut to this position, damping rod should be out also.

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    This is the hardest bit, insert the fork spring,insert the spacer & guide while holding the piston rod up from the bottom near the fork tube with one finger, grab the piston rod nut with the small pliers as you drop the spacer(I got by using the larger pliers) push the spacer down by hand while holding the rod nut to lock it in this position again under the nut.

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    Use the screwdriver once again to wedge open & insert the 12mm spanner under the nut, use the 14mm rod nut spanner & tighten the rod nut back down to the seated position, push down firmly with the 12mm to compress the spring so a full tighten can be achieved without the cylinder spinning, install the top cap.

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    Screw the top cap onto the fork outer tube, done :cool:

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  2. kz1000a

    kz1000a Member Premium Member

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    Ahhh, now I understand how you are using the electrical tape as a fork seal driver.
    Ingenious
     
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