Thanks to electronic wizardry the 2015 KX450F powerplant is
broad and powerful, but maybe not as good as last year.
The most positive improvement Kawasaki made to the 2015
KX450F was the addition of a 270mm front rotor.
Q: ARE THE SHOWA SFF-AIR TAC FORKS
AS GOOD AS THEY SAY?
A: No, they aren’t. These are the most
complicated and difficult-to-tune forks ever made.
Between their three different air pressures, 20 different
compression and rebound settings and four different
oil-height adjustments, a rider has 420,000 tuning
combinations to work with.
We tried as many settings as possible during our tests
and never found the sweet spot. It’s important to note
that the SFF-Air forks worked with the stock settings,
but they didn’t work very well. And, every logical
modification that we made alleviated one complaint
while producing two new ones.
That doesn’t mean that we didn’t find a setting that
we liked—just that our settings are so far away from
Showa’s recommended specs that they sowed seeds of
doubt in our final numbers.
Q: HOW DO THE SHOWA SFF-AIR
TAC FORKS WORK?
A: Think of the Showa SFF-TAC forks as a
submarine. Much like a submarine, the TAC (Triple Air
Chamber) fork has three different air chambers.
(1) The inner chamber, which would be where the sub
crew lives and works, is the most important part of the
sub (and TAC fork). Pressurized at 145 psi, the Showa’s
inner chamber works as the main fork spring.
( 2) The outer chamber surrounds the inner chamber. It
is the fail-safe system both on a submarine and a Showa
SFF-Air fork. It protects the inner chamber of the
submarine from terminal damage, while on the Showa
fork it works as a low-pressure chamber, 7. 5 psi, that
allows a fork seal to blow without leaking air pressure
from the high-pressure inner chamber.
( 3) Finally, a submarine has balance chambers that
allow the submarine to surface or submerge by changing
the pressure inside these tanks. On the Showa SFF air
fork, the balance chamber, located on the lower right
fork leg, provides air pressure that works in the opposite
direction of the other two chambers. While the inner and
outer chambers both push the fork downward, the
balance chamber pushes the fork upward. What’s the
point? Changing the air pressure in the balance chamber,
set at 135 psi stock, can make the fork rise or fall (think
surface or submerge) by counterbalancing the pressure in
the outer two chambers. It also keeps the SFF-Air from
the common air fork problem of topping out—by pulling
the fork up when the air pressure tries to push it down.
Q: HOW DO YOU TUNE THE SHOWA
SFF-AIR TAC FORK?
A: The options are unlimited, but here are the big
five tuning areas.
Inner chamber. The inner chamber is the actual
fork spring. It has an air pressure range from 87 psi to
187 psi, with 145 being the stock setting. Much like last
year’s Kayaba PSF air fork, increasing the air pressure
stiffens the spring rate, while reducing it lowers it.
Outer chamber. The big plus of the SFF-Air’s outer
chamber over the Kayaba PSF air fork is that it is the
only air chamber that is sealed by a fork seal. And since