Hi there
You would be better getting a manual for this bike to clarify the fork weight, quantity and air gap.
general rule, older jap bikes (heavier) use about 10 weight oil. Forks always require an air gap between the top of oil and fork cap. This should be with no springs in place . Both legs should have the oil replaced at the same time. and i usually change the oil in my forks every 2 years depending on milage and storage conditions.
hope this helps
Busa Boy
April 2009