At MX1 we never stop testing. Our newest set-up is for the WP 4CS forks that come on 14-16 KTM and Husqvarna models. This version, called APS (advanced progressive system) required thinking way outside the box. The left fork utilizes bypass technology found in high-end off-road race trucks, meaning progressive compression dampening. This enables plush initial action that gets stiffer as it goes through the stroke. In addition, it frees up the rebound, letting it return faster to follow the ground better and eliminating the dreaded "packing" associated with these forks on successive bumps. The right fork handles the rebound dampening and houses a hydraulic piston/cylinder unit that eliminates bottoming. Adustment still works the same as stock, only now the fork is calibrating itself due to the progressive internal design, This set-up works best for vet riders, pros should stick with the proven Stage 3 fork mods previously tested by MXA. The photo shown is of Jody Weisel doing what he does, racing at Glen Helen REM races every Saturday. He is currently using this set-up, which says a lot, considering he has tested virtually every different type of modification available for these forks. The cost is $595 + oil. Look for a review in the pages of Motocross Action Magazine coming soon.
We did the suspension on this bike for our friends at Dicks Racing, It featured our exclusive 4CS fork mods with a complete revalve, additional low speed compression adjuster, and hydraulic bottoming control device. The shock got a full revalve, bladder reservoir with blue cap, and x-trig preload adjuster. Lots of hours went into testing, taking this bike from great to awesome. Look for a full full review in MXA magazine soon...
It is no secret that the current WP suspension has not gotten good reviews. In order to keep the forks from blowing through the stroke, they have to be valved very stiff. This causes harshness, if valved softer, they blow through and bottom. We Have the ANSWER...Our 4CS fork package addresses all of the problems. An additional compression adjuster is added to the bottom of the compression fork that gets rid of the harshness and doubles the adjustability. We also add a BCS (bottoming control system) that virtually eliminates the hard spike associated with bottoming.($575) With the big problem out of the way (the forks), we revalve the shock for more control throughout the stroke that complements the newfound fork perfomance. ($195) Springs and oil are not included in the prices above. Please fill out the service order form to initiate service, Thanks.
We did the suspension on this KTM 300SX built by Dicks Racing. Countless hours went into the settings developed with 500 National MX champ Chuck. After finishing our test on the KTM 300SX, we decided to do a 250 2-Stroke as well. Given Chucks history as a Factory Husky rider in the late 70's, the re-emergence of the brand was a logical direction to go. The setup for this bike was a little more forgiving than the 300sx tested earlier, using a more normal midvalve and stock shock piston. Look for a full review in the pages of MXA magazine coming soon.
Riding the 2013 MXA KTM 350SXF, Chuck emerged victorious after 2 hard fought moto battles with the best riders in the world. Claiming the MX1 Suspension to be "perfect" and the reason for his success, we know he is a great rider who is humble enough to give us all the credit, he however had to do the racing. He had raced the bike stock a couple weeks before the event and was "not happy" with the suspension performance that he labeled as "scary" on Glen Helens infamous downhills with huge bumps. He also complained of harsh action, while experiencing "blow through" at the same time as well as the shocks inability to hook up coming out of corners with acceleration chop. We fixed all the problems, due to the fact that we have been testing with the new linkage KTM chassis since it came out 2 years ago. Loof for full review in the pages of Motocross Action Magazine in the near future.
After extensive testing of both the 2013 CRF450 and KX450F, we have made big improvements on both bikes. Starting with the forks, internals are revalved for a plusher ride and more rebound control. Air is evacuated from the forks and replaced with NITROGEN that doesn't pump up to a higher pressure after a few minutes of use. The shock mods are matched to the forks with the correct spring installed for different rider weights. The end result is a suspension package that is balanced together for a safer and smoother ride that lets you go faster with confidence.
WHAT STANDS OUT?
Here's a list of things that stand out with MX1 Suspension's YZ450F setup.
Forks. The biggest problem with the YZ450F forks is that they are out of balance with the stiffer rear. Thus, if you can only afford to fix one end, work on the shock. If you would like to get both ends super-tuned, however, here is what MX1 Suspension did to our YZ450F forks. First, they installed stiffer 0.49 kg/mm fork springs. The stiffer spring rate held the forks higher in their stroke, but, most importantly, it allowed MX1 to change the compression and mid-valve to a much plusher setting. This allowed the forks to flow better through their travel, while depending on the spring for bottoming control. Unlike other Kayaba forks, the YZ450F forks do not have a "free bleed" hole in the piston, which means most previous Kayaba fork knowledge cannot be applied to the YZ450F. MX1 tried multiple rebound settings to compensate for the lack of free bleed, eventually finding the right combination to match the springs. Every MXA test rider loved the forks. One or two clicks in either direction made a noticeable difference in feel.
Shock. We stayed with the stock shock spring. It is well-suited to the target weight of the typical YZ450F rider. The main goal was to get plusher compression without introducing blow-through. How can you make the shock feel softer without having it bottom? MX1's answer was to reduce the size of the shock's "free bleed adjuster passage." This mod was combined with lighter compression damping to make the shock move more freely in the first two-thirds of the stroke. In addition, an old school air bleed circuit was added to ensure air-free performance. In MXA's opinion, the MX1 shock would have worked well with the stock forks because it would have lessened the stinkbug stance and allowed the chassis to ride level. But the combination of front and rear MX1 mods was pretty sweet.
Fork adjusters. MX1 built us a set of special compression adjusters that could be clicked by hand. This made testing and setup much easier than trying to wedge a screwdriver into the Kayaba slot. Unfortunately, making the KTM-style knobs is a complicated process, and the cost is $145.00.
Every test rider liked this feel, because it didn't force them to choose between running the shock stiff to avoid bottoming or soft to get a good feel through the bumps. The MX1 shock handled both well. What's the Squawk? No complaints. MXA Rating 5 stars. We loved the MX1 forks mods and liked the shock (Although not as much as the forks). MX1 figured out how to make WP suspension components plush without bottoming. That is like an ice cream sundae that doesn't make you fat. Good stuff.
1980 AMA 500 Champ Chuck Sun's tale of living with a Service KX500.
After riding the box-stock KX500AF for just a lap, I wrote up a list of a dozen changes that I thought it needed. And I knew just the man to help sort out my issues — Richard Wilk of MX1 Suspension in Roseville, California. Richard had helped me with both my Hondas and KTM's over the last few years, so I handed him my list and we set about ironing out the trouble areas.
Forks: A lot of the KX500AF frame's cornering issues were caused by insufficient low-speed damping (insufficient for a 500cc engine, but not for a much mellower 250 four-stroke). MX1 increased initial low·speed compression damping to achieve a higher ride height, which allowed me to turn under diesels at will. MX1's fork revalve eliminated the midstroke spike, but could handle bottoming resistance with ease while still using the standard fork springs. Increased rebound settled down a busy front-end without packing on downhills. The MX1 fork revalve cost a modest $195.
Shock: The MXA test riders had installed a stiffer shock spring already, so Richard Wilk increased the rebound damping to match the new spring rate.
The million dollar question: Can I go as fast on the Service Kawasaki KX500AF as I can on a modern 450 four-stroke? Yes—at least for a few laps. Could l win on one? I did win my class at the amateur portion of the Glen Helen National and made the top five in the younger age groups. And if you put a 21-year-old Chuck Sun on the KX500AF (which is how old I was when I won the 1980 AMA 500 National Championship), I think I could have won the 2009 Glen Helen National—and I'm not talking about the Two-Stroke Challenge.