ASK THE MXPERTS: THE CHEAP FIX FOR KTM 4CS FORKS
I refuse to send my 2015 4CS forks to a suspension shop to have they revalved because I’ve been burned by this in the past (when the forks came back worse than they were when I sent them there). No pressure on MXA, but I want you to tell me how to make my 4CS forks feel better for free. I am running the compression clicker all the way out and they still feel too stiff.
There is no doubt that the 4CS forks are an improvement over what came stock on KTM in the past ten years, but they still aren’t on a par with Yamaha’s Kayaba SSS suspension, but then neither are the forks on Suzuki, Kawasaki or Honda.
You aren’t the only rider to complain about the harsh feel of the production 4CS fork. The MXA test riders set off alarms when we first started testing the forks because instead of the slower test rider going out on the clickers from the stock 15 clicks out setting, our Pro test riders also turned the clicker out. This never happens. Normally the Vets go out on compression and the Pros go in. When the faster test riders, who are very proud about their need for everything to be stiffer, turned the clickers out from the stock numbers we knew there was an issue.
The development work on the 2015 4CS forks for all USA-bound KTM’s was done in-house by KTM‘s American test department along with the WP Factory Services staff. Based on their input, the valving, shims, settings and oil height were sent to Austria to put put into every 2015 KTM and Husqvarna production bike.
MXA checked all the specs and had the 4CS forks on our KTM 350SXF taken apart. The only thing that seemed amiss was that the 4CS spec sheet called for the oil height to be set at 100mm from the top of the fork leg. Our 350SXF had 10mm too much oil. We checked our Husqvarna FC450’s forks and then too had the oil height higher than the book called for.
We removed 10cc, which is the equivalent of 10mm, from both forks. Surprise both the slow and fast test rider felt that the forks were more absorbent. The big bonus was that all of the test riders could go in on the clicker settings, which gave them more room for adjustment when the track conditions changed. There were riders and jumps that could make the forks bottom…and in this case we added 5cc of oil back into the forks. However, the best solution is to send your forks out to have them revalved. MXA has had good luck with WP Factory Services, MX-Tech, Pro Circuit and ESR.
You don’t have to take your forks apart to lower the oil height. Simply removed the forks from your bike, take the air bleed crew out, turn the forks upside down and gently pump them over a graduated beaker until 10cc comes out. The, put the air bleed screw back in and reinstall the forks on your bike. If you are the cautious type, you could do this in 5cc increments, but we think tat 10cc will get your forks back to the the recommend oil height.