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Ultra classic fork oil change

Discussion in 'Tech Tips' started by FLHTbiker, Aug 27, 2012.

  1. FLHTbiker

    FLHTbiker Moderator Staff Member

    Nov 3, 2004
    Likes Received:
    I had borrowed this from another site and copied it for future use, so here it is.

    1. Remove ignition switch and the two screws holding the inner-fairing cap. Lifting the cap out of the way gives access to the fork top plug. I tried a 36mm socket but there wasn't room, same for a crescent, but the 36mm wrench in the tool kit was the solution. The plug is not on tight and removal is easy.

    Note) the 36mm wrench is actually a bit too large and 1 3/8" is a better fit.

    2. I used a ½" clear plastic tube cut to about 10" in length and inserted a small funnel on one end and stuck the other end into the fork top. It was a tight fit but worked. I wire-tied the funnel to the handlebars to keep it from slipping. Put a plastic bag on the tank to protect it from fluid that might spill out of the funnel.

    3. Once the top plug is removed the vacuum is released, so draining should be no problem. It indeed wasn't once the bottom drain plug was removed, and that was the biggest problem of the whole job. Those damn Phillips screws were in very tight and I almost couldn't get them off. Don't even try to remove them with a Phillips screwdriver, but instead get a #3 Phillips bit and use a 3/8" or 1/2" ratchet, putting heavy pressure on the screw while you turn it. It was close, but I got both of them without stripping the head after rapping moderately with an impact screwdriver (not an impact wrench).

    3. Once this screw is out the fluid begins to drain. My right side came out slowly at first until I used a toothpick to loosen some gunk that partially plugged the hole. There is no need to pump the forks to release all the oil, as in time (about 5 min.) the oil completely drains, all 10.8 oz. of it. It is a black, smelly fluid that doesn't resemble any hydraulic or other oil I've ever encountered. It looks like it has moly or graphite in it. Once the old fluid is out, reinstall the screw, but there's no need to tighten it as much as was done at the factory. The manual says 78-96 inch-pounds.

    4. I filled with SE Heavy (not the Extra Heavy variety), which is reportedly 15w (stock is 10w). Note that RK's require 11.1 oz., while EG's are 10.8 oz. Fill slowly about 2-3 oz. at a time, then pump the forks each time to force the oil past the damping valve. After about 3-4 pumps you start hearing a hollow sucking noise, which suggested to me that it had cleared the valve. RK's may not need to do this step-by-step pumping approach since they don't have the damper valve installed. That process took maybe 10 min. for each side.

    5. Finally, replace the top plug, do the other side as above, then replace the inner-fairing cap and ignition switch.

    This is definitely the way to change the fork oil on these bikes, IMO, and I may do this job every 10k, certainly not more than every 20k. As I said, it took about an hour, but next time I think I could do it in 45 min. now that I know the routine. Thanks to all who encouraged me to try this method.

    Last edited: Aug 27, 2012
  2. chucktx

    chucktx Moderator Staff Member

    Jul 5, 2005
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    thanks mark...

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