Q: WHAT IS THE MOST NOTEWORTHY
CHANGE ON THE YZ450F ENGINE PACKAGE?
A: Launch control. Okay, we can already hear
you sighing “ho-hum” and yawning at the idea of
another bike with launch control—after all, Suzuki,
KTM, Husqvarna and first adopter Kawasaki all have
the same basic systems on their bikes. But hold
on to your hats; Yamaha has upped the ante, even
though Yamaha uses the same button as Suzuki and
Kawasaki. How so? From 4500 rpm and at 30 percent
throttle opening, Yamaha’s launch control system
reduces horsepower much more than the competing
systems. Less horsepower translates into less wheelspin and more forward hook-up. “Ho-hum. That’s how
60 feet off the line, the horsepower ramps back up to
max power without you doing a thing. That is a sweet
deal. With the typical launch control system, the rider
gives up 4 horsepower all the way until he shifts to
third gear. With the Yamaha Launch Control System
(YLCS), full power is restored once the rpm and
throttle position sensors prove to the ECU that the
bike is no longer in roll-on power mode. It will
automatically shut off when you shift to third.
Q: WHAT CHANGES DID YAMAHA MAKE
TO THE 2016 YZ450F CHASSIS?
A: You don’t need Dr. Watson to tell you that
Yamaha’s goal with the YZ450F engine was to boost
low-to-mid power to complement the already amazing
top end. As for the chassis, Yamaha is trying to chase
away the demons that its frames have been tormented
by at turn-in for the last decade. The 2014 frame was
a step in the right direction, but the loose feeling on
the entrance to corners was not totally eliminated. For
2016, Yamaha’s engineers focused their attention on
“refined stability when aggressively entering corners.”
They attacked the chassis with a six-point modification
program, which will retrofit on 2014–’ 15 YZ450Fs.
Here is the short and tidy list of the Yamaha chassis
(1) Triple-clamp offset. The fork offset has been
changed from 22mm to 25mm. This may seem like
an earth-shattering move on the geometry front, but
in reality it is just a return to the previous offset. The
3mm offset change decreases the amount of trail in
the front wheel. This change in trail has a symbiotic
relationship to the next chassis change that Yamaha
made for 2016.
( 2) Shock spring. The rear shock spring has been
changed from 58 N/m to 56 N/m. Normally, a lighter
spring rate is chosen to accommodate a lighter rider,
but Yamaha is still aiming for its original 175-pound
target audience. So, why go to a softer shock spring?
To allow the rear of the YZ450F to settle a little
deeper into its stroke. On the positive side, this
settling improves overall traction at the rear wheel.
On the negative side, it drops the rear of the bike and
kicks the steering head angle out, which increases
trail. Thus, to get the trail back to where it needs to
be, Yamaha paired the greater offset triple clamps
with a softer spring rate to bring the dimensions
back into sync.
( 3) Chassis stiffness. To maximize the frame
geometry, Yamaha wanted to stiffen the chassis torsionally to lessen twisting loads under hard acceleration. The engineers did this with wider forgings at the
swingarm pivot. A close look at the aluminum parts
next to the rider’s boots will reveal that they extend
rearward 12mm more than last year’s forged pieces.
This provides not only stronger support for the swingarm and rear motor mount, but lessens twisting of the
chassis to improve stability and bump absorption.
( 4) Head stays. To fight against any engine shake
or chassis flex at the front of the frame, the head stays
are bigger, thicker and stronger.
( 5) Footpegs. The YZ450F footpegs have been lowered 5mm. This change is not made to the frame or
the mounting brackets but to the footpegs themselves,
which means that they will retrofit on the 2014–’ 15
models for riders who want to lower the bike’s weight
or make the cockpit a little roomier.