How do I put oil in the forks of an 04 Honda crf450r?

Your bike has dual chamber showa forks. Remove the forks from the bike. Record the clicker positions and back off the clickers completely. Remove the top fork cap. Drain the oil from the outer chamber into a drain pan. Turn the top cap back in acouple threads to protect the threads. Flip the fork upside down, remove the bottom rebound adjuster. Push down on the lower fork tube, and insert a pushrod holding tool or an apropriot sized open end wrench under the locknut. Remove the adjuster from the pushrod, push down on the fork tube again and remove the holding tool. Turn the fork over again, remove the top cap, and pull out the inner chamber. Remove the compression chamber valve assembly. Drain the oil from the inner chamber. Pump the pushrod afew times to get all the oil out. This is the time to change your seals and bushings if needed. TO RE-FILL : Pour aprox. 6.6 oz of fork oil of desired weight into the inner chamber. Pump the pushrod afew times to expel the air. In your owners manual, there are level specs. Measure from the step at the bottom of the inner chamber inside to the top of the fork oil. Adjust oil level to desired measurement. Re-install the compression valve assy. Re-install the inner chamber in the fork tube assy. Fill the outer chamber with aprox. 12.5 oz of the fork oil you chose. Re-install the top cap into the upper fork tube. Re-set your clickers and install the forks back on the bike. It sounds complicated but it's really quite simple if you take your time and pay attention to what you're doing.

http://www.motosport.com/dirtbike/tv.php

Pretty much the same steps except doing the seals.