Because Yamaha got it right with its SSS suspension eight
years ago, they don’t have to play fork roulette every year.
The Kayaba shock is easily accessible on the left side of the
bike for preload or clicker adjustments.
Q: WHAT ABOUT THE SLANT-BACK ENGINE
A: We love the creativity of both Yamaha’s and
Husaberg’s backwards engines. They work by harnessing
the rotating mass and gyroscopic forces of the engine’s
moving parts to make the bike feel lighter in roll, pitch
and yaw. However, the real benefits of the slant-back
design are muted by the fact that neither the YZ450F
nor the now-departed Husaberg FE450 were light
enough to take full advantage of the physics involved.
Thus, you have a Yamaha engine department trying to
make the bike feel smaller and lighter, while the chassis
department builds a bull moose of a bike that all but
nullifies the highfalutin science.
Q: HOW DOES THE 2015 YZ450F HANDLE?
A: The handling is better in 2015 than it was in
2014, which was better than in 2013. And even though
the MXA wrecking crew has been critical of the
front-end response of the YZ450F since 2007, we are
beginning to warm to the YZ450F’s geometry.
By no stretch is it the best handling bike on the
track, but Yamaha’s engineers, especially in the engine
division, are nibbling away at the loose feel at turn-in.
Still, changes to the powerband, gearing and motor
mounts aren’t enough. It is obvious that the chassis
department should contribute more to the solution, since
the chassis is obviously the problem. The YZ450F is too
tall in the rear. It is too wide at the radiators. It is too
YZ450F racer, the new powerband and awesome
suspension can mask the most glaring flaws in the design.
We opted to run 105mm of sag to bring the rear of the
chassis down, aided by a longer Pro Circuit linkage, while
moving the forks up and down in the clamps to find the
balance we wanted. Equally important to the YZ450F is
the choice of front tires. Although the stock Dunlop MX52
is okay, we would choose terrain-specific rubber, like the
MX32 or Bridgestone MX30, for our SoCal tracks. A good
front tire civilizes the YZ450F at tip-in.
Q: WHAT DID WE HATE?
A: The hate list:
(1) Brakes. What brakes? Kawasaki and Honda have
responded to KTM’s superiority with oversize rotors for
2015. Yamaha and Suzuki have not. We’d rate the YZ
brakes second to last and the RM-Z brakes dead last.
( 2) Yamaha-thumb. Blood in the glove is never a nice
thing. A grip donut can stop the bleeding.
( 3) Dzus fasteners. Love the idea, but the two fasteners on the side of the radiator wings took flight. Why?
Because when your knees hit the shrouds and the plastic
flexes, it unlocks the quarter-turn fasteners and they fall
out. Plus, your leathers can catch on the D-rings and flip
them open. Put tape over them, remove the D-rings (and
use a screwdriver) or switch back to bolts.
( 4) Gearing. Experiment with a 49 or a 50 for your local
( 5) Radiator wings. You can’t do much about how
wide the YZ450F is at the radiators, but Cycra shrouds,
designed with the help of the JGR team, not only make the
bike narrower at the gas tank but make it breathe better
and weigh a lot less.