The oil in the fork of your dirt bike is essential to proper function. In order for the fork to function correctly, there must be a constant and very specific amount of oil in the fork at all times. Over time, the fork of your dirt bike may start to leak oil. If this starts to happen, you will notice a difference in how your XR250 functions and handles. You can fix this problem by disassembling your fork and replacing the dust and oil seals.
Dissasemble the Fork
Loosen the rebound adjustment screw all the way. This is the screw at the very top of the fork.
Thread the fork cap out of the outer tube by turning it counterclockwise out of the threads. Slide the outer tube down.
Pull the exposed spring down and insert your wrench above the spring onto the lock nut.
Loosen the cap off of the damper rod and lock nut by loosening the lock nut counterclockwise. You can now pull the cap completely off of the assembly.
Remove the spring by sliding it out of the tube.
Remove the push rod that is inside the damper rod by sliding it out.
Discard the oil in the fork into an empty container. Pump the outer tube a few times to ensure that all of the oil is out of the damper rod.
Remove the dust seal by prying it out with a screwdriver. The dust seal is the black ring farthest away from the top of the fork.
Remove the retaining clip by prying it out with a screwdriver. The retaining clip is right above where the dust seal used to be. Be sure not to scratch your fork. Slide the clip out of the way.
Remove the outer tubing by popping out the seal. Do this by pulling the outer tubing off of the inner tubing. You will find a seal trying to hold the two together as you try to pull them apart. Just apply pressure until you can make it past the seal.
Remove the bushings from the inner tube by sliding them off. They will be at the very top of the fork and will slide right off.
Remove the flat washer and seal by sliding them off of the tube in the same way you removed the bushing.
Slide off the dust seal and retaining clip.
Reassemble the Fork with New Seals
Stand up your inner tubing and secure it in a vise.
Grease your new dust seal and slide it on, followed by the retaining clip and new oil seal. Use seal grease with all of the components. You slide these components on in the exact opposite order of how you slid them off earlier.
Slide the washer onto the tube, followed by the outer bushing and inner bushing.
Slide the outer tubing onto the inner tubing.
Use your seal driver to drive the bushing and washer until they bottom out. Place the seal driver right under the washer and then tap the washer into the bushing. You will be able to hear a noise difference when you tap when the washer is completely in.
Drive the oil seal into the bushing and washer until it is completely seated. Do this in the same manner as previously done. Place the seal driver under the oil seal and tap it into the washer.
Reinstall the retaining clip until it clicks into place. You can use the seal driver for this step. Place it under the retaining clip and tap it into the oil seal.
Slide on your dust seal using your fingers.
Slide the push rod into the dampening rod.
Fill the cylinder with oil. Lift the outer tube a few inches a couple of times to settle the oil.
Run the inner damping rod up and down a few times to fill the whole cartridge with oil.
Add oil using the fork oil level tool. The appropriate level of oil in the XR250 is 82 millimeters as measured from the top of the tube. The fork oil level tool will slide right into the inside cylinder of the fork.
Pull the damping rod up and reattach the spring with the washer and fork cap in the exact manner it was before you disassembled it.
Tighten the assembly by rotating clockwise with a wrench between the spring and lock nut and use a socket to tighten it at the top.
Pull up the outer fork tube and thread the fork cap back into it by screwing it in clockwise.
Reattach your fork to the rest of the body. Tighten your rebound screw at the top.