The forks on all these motorcycles connect the handlebars, front wheel and frame.
The correct procedure for setting the fork oil level on any FLH, including the FLHX, is arcane. You put the right amount of oil in and then, using a special tool that looks like a bicycle pump, you take just a little bit out. Worse, the tool is sold only by Harley-Davidson. When a clever service writer really wants to snooker you he will tell you something to the effect of your right fork taking 11.2 ounces of oil but your left only taking 11.1. The numbers he gives you are the product of the arcane official Harley procedure, not any mechanical difference between your forks.
1. Measure 11.2 fluid ounces, which is 300 milliliters, of Harley Davidson fork oil or the equivalent into a measuring cup. Pour the fork oil into the top of a dry FLH fork from which you have removed both the fork cap bolt and the fork tube plug but not the fork spring.
2. Push the fork tube into the slider several times to remove trapped air from the fork tube.
3. Loosen the metal set ring on the front fork oil level gauge by loosening the thumbscrew. Measure 125 millimeters from the end of the oil level gauge tube with a metric ruler.
4. Adjust the metal ring on the front fork oil level gauge so that the bottom of the ring is exactly 125 millimeters from the end of the gauge tube. Tighten the thumbscrew.
5. Push the fork oil level gauge handle all the way into the gauge. Set the metal ring on top of the fork and insert the gauge tube into the fork.
6. Pull the fork oil level gauge all the way up to suck out any excess oil in the fork tube. Expel the excess oil into a drain pan and repeat the process for the other fork tube.