Dubach trusts Enzo for his suspension needs. For $360 they
will revalve the forks and shock for better performance.
Injectioneering throttle body mods significantly improved the
YZ450F throttle response. This is a Pro-level modification.
THE DR.D ENGINE PROGRAM
DR.D started the modification project with three basic
steps.
Exhaust: Obviously, Doug based the YZ450F project
bike on his wraparound DR.D NS- 4 exhaust system. It
broadens the power and makes the power feel torquey
across the range.
Throttle body: Doug installed an Injectioneering
throttle body mod to the YZ450F’s fuel injector. This
reshaped butterfly valve is well-respected for its ability
to liven up the throttle response and bottom end of any
fuel-injected bike. The Injectioneering throttle body made
for a smoother transition into the midrange. It took a few
laps to get used to the new feel, as there was no turbo
lag at the crack of the throttle, but we loved what the
Injectioneering throttle body did to the powerband.
Mapping: The final adjustment was to fine-tune the
mapping. Although DR.D builds its YZ450F exhaust
system to run with the stock map, MXA has extensive
mapping experience on the 2014 YZ450F, and we felt
we could get more power with the addition of richer fuel
maps (we did not change the ignition map). During the
mapping sessions, we employed three test riders,
including Doug himself, and within two maps we cleaned
up the jetting and increased power for a crisper feel.
The exhaust pipe, Injectioneering butterfly, and
3-percent-richer map on the bottom and mid (six-percent
richer on top) were the only engine mods made on the
DR.D YZ450F. That was it! MXA test riders are usually
begging for more power, but technology has advanced
enough that instead of looking for more power, we are
trying to massage the available power into a more
usable profile.
WORKING ON THE CHASSIS
With Yamaha’s new design and the emphasis on
centralization of mass, the YZ450F’s handling is much
improved over the rather atrocious handling of the 2010
through 2013 YZ450Fs. The Yamaha engineers made
major upgrades to the YZ450F handling, but there are
still remnants of the previous model’s peccadilloes—they
just aren’t as severe. In a nutshell, the YZ450F is loose
going into corners and, when combined with the barky
low end, this trait makes it hard to get low and stay
down while turning.
The first thing we did to improve the handling was
to install a DR.D radiator lowering kit, which moved the
water weight down a significant 24mm. Step two was to
change the triple-clamp offset from 22mm to 20mm with
an Applied triple clamp. The combination of the lower
radiators and increased trail allowed the bike to settle
into the corners, making the YZ450F more of a point-and-shoot machine. Step three was to work on the balance of
the chassis to get the bike to feel level. This gave riders
more confidence; they could flow from corner to corner
without having to fight the bike.
THE SSS SUSPENSION PACKAGE
As far as the suspension goes, it is hard to top
Yamaha’s stock Kayaba SSS suspension. Nine times out of
10 you can find a good setting with just a careful adjustment of the sag and a few clicks. Doug has always raced
with Enzo suspension, so he sent the SSS components to
them to fine-tune the feel for our weight and speed.
