The YSS fork upgrade kit contains a narrower fork spring, a fork valve and an adjustable fork stem lock.
The fork valve changes the flow of oil in the fork in both directions, and the fork spring causes the spring to behave tighter.
With the handlebar cover it is possible to readjust the fork spring preload: by rotating the adjustment screw you increase the pressure and therefore the fork spring preload.
YSS supplies this vehicle specific kit as a whole set. Attention: it is essential to follow the assembly instructions in the attached PDF