RIDING IMPRESSION
P46
WHAT'S NEW?
Like it has in the past with the
WR line, Yamaha simply took
the current YZ250F and turned
it into a prime off-roader for both
the casual trail rider and seri-
ous racer. Like the YZ, the WR
is highlighted by its reversed
(exhaust port in the rear, intake
in the front) and rearward-in-
clined cylinder, and wrap-around
exhaust system. This unique
engine configuration, which also
allows for the fuel tank and air-
box assembly to swap positions,
goes a long way in improving
mass centralization by moving
the heavier fuel cell lower and
more centralized in the chassis
and the lighter airbox up high.
And what does all that mean?
Improved handling.
Another advantage, espe-
cially for the off-roader, is that by
placing the air filter higher up in
the frame and farther away from
the rear wheel, the filter will stay
cleaner longer and make water
crossing far less stressful for the
rider. There is less chance of
drowning out the motor.
There are some power ben-
efits of the new engine design,
as well. Yamaha engineers
are able to provide a straighter
intake shot into the cylinder for
improved and more efficient
combustion. The cylinder is
also offset 3.5mm forward of
crankshaft centerline to reduce
piston-to-cylinder wall side
thrust (friction) during the power
stroke. Less friction doesn't
sound like much but it means a
bit more power.
Another significant difference
worth noting is the WR's new
wet-sump lubrication system;
this design does away with the
WR's former external oil tank and
lines, and also allows for a more
compact engine, despite hous-
ing the motor for electric start-
ing. The WR, however, retains
the manual kickstarter as a back
up, and for quick getaways for
dead-engine-start races.
Transmission is a more versa-
tile six-speed, compared to the
YZ's five-speed, and the clutch
2015 YAMAHA WR250F
If you think the WR
looks just like the YZ
with lights, you're right,
because that's pretty
much exactly what it is.
