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Discussion Starter · #1 · (Edited)
Good morning,

I am looking at changing the fork oil on my 81 CM400A, manual only shows complete disassembly/rebuild of the forks.

Can I drain it from the bottom plug, and just add fluid from the top (If I remove seals)?,

or, would I have to pressure fill fluid from bottom of fork with oil pressure bottle?

or, if I can't rig up a oil pressure bottle, have hose on a fitting in drain plug hole, and slowly extend fork sucking fluid into the fork?

Thanks guys
 

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You can just drain and refill the forks, but if I recall correctly, the specs for refilling (so many inches or millimeters from the top of the tube) involve removing the caps and springs, and then collapsing the forks completely. This will best be done with the forks off of the bike. This will also make it easier to drain the forks, as you can pump them with the plugs out and the caps still on.
I'd be tempted to drain them, remove the caps and springs, fill them partially with ATF (with the plugs replaced), pump them a dozen times or so to slosh the fluid around inside, and then drain them again. You may be amazed at how much gunk comes out when you do this. Maybe repeat until the ATF comes out clean, then drain and fill per the manual specs.
 

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To do this you do need to support the front of the bike, jackstand or jack to hold it up, since the fork caps have to be removed for fill and drain. Once up and supported remove the caps and with a drain pan positioned to catch oil squirting out remove the drain screw. NOTE: this is a really foul stinky process so good ventilation is suggested, clothespins for the nose might help. :lol:
Once the oil is drained then you can refill with the amount of oil listed in the FSM. The residual amount that doesn't drain is less than 10 cc's, probably less than 5.
 

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Be sure not to jack up the bike in a sunny spot on a hot day to drain your forks. I was amazed at the distance fork oil can squirt. Also tie a rope to hold your handlebars, bungee cords will be too springy.
Ask me how I know... ?
 
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