KTM EXC EXC-F Forks
WP introduced the Xplor fork. It replaced the previous Open Chamber (OC) and 4CS Forks. The Xplor has compression and rebound adjustment on both fork caps with no adjustments at the base. We think the design brief was a light fork, easy to adjust, with setting aimed at Extreme Enduro over Offroad competition. In use the fork feels very active, lightly sprung with an almost trials bike feel. We have seen and tested a variety of aftermarket answers from base adjusters to one or two main pistons, all adding to the cost and all yielding mediocre results. After analyzing how the fork functions on our linear actuator dyno, we can utilize the existing design from WP and just change the setting.
These years used the OC fork and the 4CS. While the OC forks hadn't changed in architecture since the previous version, the 4CS was all new. It's 4 chamber system which took some real understanding and while there were a host of aftermarket kits available for this fork, we took the time to analyze the fork, understand where WP made some errors in the pressure balance and had systems in place in the fork to allow the fork to function while suffering pressure balance problems. We change the settings to get the pressure balance as even as possible, work on some of the 4CS's nasty traits like the high initial force that makes the fork stiff for trail riding while being too soft once the pace picks up. The original adjustment is retained and you get a very good fork with a setting change only.
The first real change happened to the fork since 2003, with the damper rod changed from a 14mm diameter to 12mm. Less displacement dampening, so the base valve becomes less critical. It was a great fork and funnily enough, it's still great architecture for an offroad fork. The preload adjusters were a great touch.
Bringing the EXC range into line with the SX range, 48mm forks for 2003. The first few years used a 3 bushing arrangement that contributed to drag with dubious other benefits. The fork reverted back to a 2 bush after a few years.
The new 43mm WP USD fork was introduced. It ran a 14mm damper shaft, 28mm cartridge and was frankly a good fork for it's time. In hindsight the settings were horrendously soft and I don't think WP owned a shock dyno at that point. The 43mm fork is still in use today in the KTM and Husqvarna 85SX plus the Freerides. We still have springs for the early forks and we can get them working far better than anyone could in 2002.