PD Fork Valves
& Assembly Instructions

 
 

PD Fork Valve Info

The new PD Fork Valves give that progressive and controlled feeling of a cartridge fork. Radial computer designed valve housing made of 6061 T6 aluminium for light weight. 65 Rockwell hardened for long life and appearance. Damping adjustable and tuneable to any application. Easy to install. Extremely cost effective. Can be used for On- and Off-Road, Racing and Touring. Fully tested and proven. To suit all brands of motorcycles with conventional forks.
• Oil Levels & Viscosity •
• PD Valve Assembly •

PD Fork Valve 425
(Above: 42.5 mm PD Fork Valves)
 PD Fork Valves
Phone +61 (08) 8284 8033 - Y.S.S. AUSTRALIA - Lot 257 Heaslip Road, McDonald Park SA 5121

YSS PD Fork Valve Assembly Instructions

Tools required

  1. Drill Motor and 6 or 8 mm Drill
  2. Allen Socket 8, 10, 12 or 14 mm
  3. Tape Measure
  4. Tubing Cutter
  5. YSS Fork Oil

Recommended

  1. Choose correct fork spring for your motorbike.
    Consult YSS Service Center: YSS-AUSTRALIA - Telephone: +61 (08) 8284 8033
  2. Check the proper fit before installation.

Instructions

Note: All these steps should be done by a suspension mechanic.

  1. Take off the fork from the motorbike.
  2. Disassemble the fork (don't remove the seal)
  3. Take the fork spring and damping rod out.
  4. Place YSS PD Valve on the top of damping rod.
  5. Put the step on YSS PD Valve into the large hole. You must cover it completely (as shown in Picture 1).
  6. The inner diameter of fork spring must be at least 3-4 mm larger than the PD Valve plate (less than 3 mm - use with some models of PD Valves which have side flow space).
  7. Drill the compression hole in addition - the distance between the holes must be at least 10 mm apart (as shown in Picture 2) - the sizes of damping rods are as follows:
    • 4 holes of 6 mm. (1/4 inch) for 175
    • 4 holes of 8 mm. (5/16 inch) for 235
    • 6 holes of 8 mm. (5/16 inch) for 265 and bigger
  8. Chamfer and deburr in and out of the compression holes.
  9. Check the YSS PD Valve (spring rate 7 Nm for 175, 235, 265, 290 and 12 Nm for 310, 335, 360, 425 with 2 turns of valve spring preload).
  10. Tighten the jam nut of YSS PD Valve.
  11. Assemble the forks as in your manual or do the reverse of reassembling.
  12. Drop YSS PD Valve down the tube to sit on the damping rod with the PD Valve spring facing up.
  13. Insert the fork spring into the inner tube on the top of YSS PD Valve.
  14. Add the fork spring spacer (cut them for 14-17 mm - same as the thickness of PD Valve, more or less depends on the fork spring preload requirement).
  15. Install the fork fluid by removing the fork spring and PD Valve, use the oil viscosity as recommended by YSS manual or manufacturer (10W for standard or 15, 20 and 30W for optional).
  16. Pump the fork for bleeding.
  17. Install YSS PD Valve and check the oil level.
  18. Install the spring and spacer.
  19. Re-check the spring preload.
  20. Install the fork caps and push on them.
  21. Tighten all bolts.
  22. Assemble the forks back to the motorbike completely.

Tuning Options

Tuning Standard Optional Advantage
(1.) Oil Viscosity 10W 15W, 20W, 30W More or less rebound depends on viscosity to make stability
(2.) Valve Spring Preload (3.) Two (2) Turns 0 to 7 Overall firmness, controlling the speed of front end dives under braking
Valve Spring Rate 7 N for
175, 235, 265, 290

12 N for
310, 335, 360, 425		 12 N



7 N		 Overall firmness and smooth ride on square shaped bumps
  1. Use oil viscosity to set the amount of rebound damping, then adjust the compression with the PD-Valve settings. The PD Valve does not affect rebound, however oil viscosity does. The primary compression adjustment is the amount of preload on Valve Spring.
  2. Measured from no tension on the Valve Spring.
  3. Two (2) turns of Valve Spring Preload for lighter riders.