FORK WORKS: KAYABA AOS FACTORY KIT SPRING FORKS

On Aug 14, 2017 Last updated Apr 9, 2018

As quickly as motorcycle manufacturers hopped on the air-spring fork bandwagon, they’re now jumping off in the face of angry consumer pressure. If not for WP’s excellent AER fork, air suspension would be all but dead. How resentful have riders become over air forks? Recently a 10-year-old boy approached Husqvarna’s Andy Jefferson at a local track and began berating Husqvarna for its switch to air forks. The brash preteen went so far as to state that no one likes air forks because “they’re junk.” Suffice it to say that air forks, on the whole, are now a negative sales feature.

There are currently three major suspension players—Showa, Kayaba and WP. That group supplies suspension for the most popular motocross bikes. Each also builds and sells “works replica” forks through the aftermarket business, each with its own special name. Showa calls its aftermarket forks A-Kit, Kayaba calls its forks Factory Kit and WP uses the term Cone Valve. Regardless of the marketing name, works replica forks have special coatings, different internals, more setup options and closer tolerances. They also have exorbitant prices.

For 2017, Kayaba is offering two different Factory Kit fork packages. The PSF-1 air fork (tested in the December 2016 “Fork Works”) and a traditional spring fork based on the Kayaba AOS system. Called the Factory Kit Spring Fork, it’s a closed-cartridge system with the air and oil separated. The closed cartridge contains displaced oil in a sealed-off chamber. The closed oil system reduces cavitation to ensure consistent damping. Kayaba Kashima coats the inner cylinders for better wear resistance and DLC (Diamond- Like Carbon) coats the inner tubes to reduce friction, increase surface hardness and aid in corrosion prevention. The visual allure of the dark, golden Kashima coating on the fork stanchions, along with black DLC coating on the fork legs, is hard to resist. Our Yamaha YZ250F forks included blue-anodized fork caps, while the black outer tube protectors added a nice touch. We drooled over our test forks and the shotgun-style-padded case they were shipped in.

THE FORKS COME WITH SETTINGS DEVELOPED ON THE GRAND PRIX CIRCUIT. WE PROVIDED DISTRIBUTOR TECHNICAL TOUCH WITH OUR WEIGHT AND SKILL LEVEL. THEY DID THE REST.

Internally, the Factory Kit spring fork uses a metal spring perch with small bleed holes to control compression. Kayaba used to make the spring perch out of plastic, but it would crack. The Factory Kit’s base valve piston and mid-speed valve are revised for more damping control. One of the extra features is a factory spring collar, which makes the end of the stroke more progressive for a softer landing. The forks come with settings developed on the Grand Prix circuit. We provided distributor Technical Touch with our weight and skill level. They did the rest. While we were pleased with the settings, understand that you may need to have the forks re-valved by your favorite qualified suspension technician.

ON THE TRACK, THE FACTORY KIT FORK WORKED WONDERS. IT SHARES ATTRIBUTES WITH THE KAYABA SSS FORKS IN THAT THE TRAVEL IS EXTREMELY FLUID, ESPECIALLY IN TRANSITION FROM SMALL CHOP TO HEAVY IMPACTS.

On the track, the Factory Kit fork worked wonders. It shares attributes with the Kayaba SSS forks in that the travel is extremely fluid, especially in transition from small chop to heavy impacts. Bottoming resistance was plush without the occasional spike that comes with the standard SSS fork. There wasn’t any point in the stroke where we thought the stock YZ250F Kayaba SSS forks performed better than the Factory Kit. The best compliment we can pay the Factory Kit spring fork is that it upped our confidence level. As a bonus, Pro, Intermediate and Vet riders could find clicker settings that worked great for them.

The digits? The retail price of the Kayaba Factory Kit spring fork is $4500. Given that Kayaba makes the Factory Kit spring fork for all major models, we would have loved to try it out on a bike with major suspension woes, such as the Suzuki RM-Z450. Note that KTM, Husqvarna and Suzuki owners will need special Xtrig ROCS triple clamps in order to fit the forks. In that case, tack on an extra $900 to the bill. For more information, please visit www.technicaltouchusa.com.