Wilbers Zero Friction Progressive Fork Springs (50mm low) / XT660Z Tenere '08-On

Please note:

10wt oil is recommended for general purpose and for more dirt road riding.

15wt oil is recommended for sport-oriented street riding.

Air chamber is 140mm with springs removed and forks completely compressed.

Instructions for setting air chamber: 

1) Remove fork spring and drain old oil. 

2) Compress fork fully with spring removed.
3)  Add oil until oil level is the prescribed distance from the top of the tube - this is your air chamber.
Piston rods should be pumped several times to dispel any remaining air before final measurement is made.