Change the hydraulic fluid in the front forks after 10,000 miles of riding.
Telescoping hydraulic front forks are found on many Harley-Davidson motorcycle models. The hydraulic fluid in the forks should be replaced after every 10,000 miles of riding. Harley Davidson also recommends changing the hydraulic fluid if you are planning to store your motorcycle for an extended period of time. The length of time required to change the fluid in the Harley-Davidson hydraulic forks depends greatly upon your skill level, but should take approximately one to two hours to complete.
1. Block the motorcycle and elevate the front wheel with a motorcycle jack so that the front forks are fully extended. Place a drain pan under the forks.
2. Remove the caps from the top of each fork tube, using an SAE wrench. Remove the drain screws from the lower end of each fork tube, using a large cross-tip screwdriver. If you are unable to break free the screws by hand, you may have to use an impact screwdriver.
3. Drain the fork oil. Replace the drain screws, using a cross-tip screwdriver.
4. Fill the forks from the top with 10 to 11 ounces of Type E Harley-Davidson fork oil. Replace the fork tube caps and tighten with an SAE wrench.