YSS Fork Upgrade Kit. YSS fork upgrade kits. A fork valve is also included for vehicles with conventional forks. Fork valves cannot be installed on vehicles with upside down forks, which are outside the scope of applicability of these kits. With the fork tube cover, the spring preload of the fork can be externally fine-tuned – by turning the adjusting screw, the pressure, and thus the preload of the fork spring increases. YSS kits come as a complete, vehicle-specific set. Filling Height (Air Chamber). YSS is the largest producer of after market motorcycle shock absorbers in the world, and its range is constantly expanding. With a 270 strong team, they manufacture over 2 million shocks per year, with a plethora of products to suit all tastes and budgets. Since its establishment in 1983, YSS has become renowned for its use of high quality components and cutting edge technology. Every part that goes into a YSS shock is designed, manufactured and tested in house at the YSS factory in Thailand.
