19. Harley recommends adding fork oil with the forks fully compressed and without fork springs or spacers. Although the volume of oil is important, since we added extra length to the fork tubes the stock value changed. A more accurate way of determining the amount of fork oil is to measure the distance from the top of the tube to the fork oil level. To use the fork oil tool, we filled the forks, set the distance (4.2 inches for a ’04 RK) from the top on the fork tube, and removed (through suction) the excess fork oil. When all you get is air in the tool, you have the proper level of fork oil.