2002 Yamaha WR 250 Fork oil capacity

1985 YZ250N, With the Fork off, Cap off, Spring out, take a clear school plastic ruler pore in 5W synthetic fork oil till it's 135mm from the top with the fork tube all the way down, till it just touches the ruler and the 135mm mark. Reinstall the spring, pacer, washer, Damping rod to cap, and install back in the clamps. I raced this bike for 18months in 1985/1986. Change the seals when they leak and toss the 38Kg Fork springs for 41Kg + springs to your riding weight. Over all was a good fork for it's time and Race tech can rebuild the fork and shock to your riding style and you're riding weight. I Miss the Fork flex on hard landings to my other New bikes. I still ride and Race the 85,YZ490 with the same fork.

Hi
You can download the whole workshop service manual that has this info and heaps more from here. Hope this helps Thanks for using Fixya. 
regards robotek