The 2008/9 R system caused many problems for the 55, 33 and DJ fork, the cartridge was a bought-in sealed item that was gas charged. The problem with was that the sealing was relatively poor and the cartridge could suck in oil from the outer leg, this overfilled the damper and created hydraulic lock. The fork became very hard and suffered from a loss of travel.
The good news is that the fork can be fixed relatively inexpensively (if out of warranty). All replacement cartridges are converted to open bath, so when installed, fixes the fork 100% with vastly improved performance. The open bath cartridge differs via the flow holes at the top and bottom of the cartridge.
Y703897 – fits 33 R/DJ 1/ 2 2008/9
Y703898>A – fits 2008 Z1 SPORT/55 R
Once installed put the following quantity oil (SAE 7.5W) into the leg:
DJ1 – 150 cc
DJ2 – 190 cc
55R – 160 cc
Put air on the other side so to find the best balance for the rider. Suggested range for model fork:
DJ1 – DJ2: 2÷5 BAR
55R : 2 ÷ 3.5 BAR
Push up/down the fork until when the fork works correctly.