You might think that the 2014 YZ is the old bike with new bodywork. Wrong-o.
Virtually every piece is new.
The idea of mass centralization is nothing new or special
to Yamaha. Honda used the term to justify the dual-muffler
design on the CRF250F four years ago. Husaberg went farther down that road than anyone with the 70-degree engine.
Even Cannondale designers talked about it in 2001,
although they never used the same terms. Here’s the idea: a
dirt bike with all its weight centralized will feel lighter and
handle better than a dirt bike with heavy parts located all
around its outboard edges, even if the two bikes have the
same total weight. In your mind’s eye, the concept makes
perfect sense: you can imagine how poorly a bike would
handle if the motor were mounted on the rear fender.
That’s the thinking that generated the reverse motor of the
’ 10 YZ450F. The head was turned around and tilted back so
that the throttle body and the injection stuff could be located
on the centerline of the bike. There’s very little mass located
aft of the countershaft or forward of the crank. There were
very practical considerations at work too. The location of the
carburetor on almost every motorcycle since the ’50s has
always presented problems. It forces the airflow to make a
90-degree turn to enter the combustion chamber, and the
rear shock is right in the way of a clean inlet. With the coming
of fuel injection, Yamaha took the opportunity to address all
that. The airflow from the filter, through the throttle body and
eventually right into the combustion chamber, is straight and
direct, courtesy of the new engine layout.
Yamaha had to deal with some engineering problems along
the way. One was the inadequate exhaust pipe length between
the exhaust manifold and the muffler. That was solved with the
“Tornado” exhaust and its spiral shape. Other solutions proved
more difficult. One was the lack of space allowed for the air-filter element. Another was the shock being surrounded by some
very hot engine parts. And biggest of all was the weight bias.
Yamaha was quite successful in relocating most of the mass
near the center of the bike. However, comparatively more of
the weight was moved from the front of the bike to the center.
Not that much was from the rear to the center, and that resulted in a more rearward center of gravity. On top of all that, the
bike actually gained weight, so any benefit from mass centralization was effectively rendered null and void.
And finally, there was the PR disaster last year with
James Stewart jumping ship mid-season. Even though
James was careful not to criticize the YZ, his actions spoke
volumes. The revolution didn’t go well for Yamaha.
NOW THE SEQUEL
Yamaha didn’t address any of its problems in 2011, 2012
or 2013, letting the momentum and the hype die. Even
though the YZ450F was innovative and unique, it was shuffled to the ho-hum file and virtually forgotten. Most riders
didn’t see any benefits, and there were obvious shortcomings. The engineers at Yamaha must have been going nuts.
They still believed in the concept, even if the execution wasn’t what it could have been.