How to Fill Fork Oil on Your Harley Ultra

The Harley Davidson service manual is very specific about achieving correct fork oil capacity. The steps to perform this service are detailed yet simple, as Bob and Mark demonstrate in this video on how to fill fork oil on your Harley Ultra.

Fill It

With the 49mm fork tube fully extended; pour, slightly more than, 24 fl. oz. of fork oil into the fork tube. Next, actuate the fork to to fill the internal dampner cartridge. Pump the fork tube until greater resistance is felt.

Hold It

Use a fork tube holder or a second set of hands. Tip You have to have your Year and Model service manual! You need to follow this procedure, fluid requirements and measurements for your year and model.

Extract It

Set your fluid extractor to 3.74″, or 95mm. Set the extractor flush, on the top of the fork tube. With the fork tube bottomed in the fork slider, extract the excess fluid. Now, your fluid level is set to the correct factory specifications.

Replace It

You can now reassemble the fork tube. Extend the fork tube from the slider and install the progressively wound fork spring in the same direction as it was removed.

*NOTE* The tube is progressively wound. The “tighter” end should face downward, (or go in first). There are some applications where the direction of a progressively wound spring does not matter. However, that is not the case, in this service.

Next, install the washer/spacer, and the (tube) spacer. The tube will stand approx 2″ above the top of the extended fork tube. That is correct and is considered to be the preload. Prep the fork tube cap with a new o-ring and teflon paste. Then install and torque to the correct factory torque spec.

Fork oil is an integral part of your front end. Incorrect fluid level, or old/tired/dirty fluid can adversely affect the handling of your motorcycle. Correct, thorough service of this area is crucial.

You will need to change your fork oil at every factory recommended service interval. You will also replace fork oil when replacing fork seals & bushings, tubes, or any time there is a need to completely disassemble the fork assembly.

Next Up: Harley Front End Install