FEATURE
PRO CIRCUIT YAMAHA YZ250F
P92
that—a pipe for the pros. It shifts
some of the YZ's power from bot-
tom to top, which is where most
pro riders like to ride, but it still
boosts bottom-end a bit. The
Ti-6 pipe seemed to be the per-
fect choice for Loretta's long and
loamy start straight, too. But it's
not all about power. This pipe
is also about five pounds lighter
than the stock exhaust system,
and it's also shorter and more
compact for improved mass cen-
tralization and, in the long run,
improved on-track handling. Yes,
$1200 is a lot of money for a pipe
but the benefits are worth it.
More power means more
stress on the motor and trans-
mission, so Pro Circuit installed
stiffer clutch springs ($69.95)
on our bike. The YZ's clutch is
already pretty strong, but with
the additional power and an
above average rider at the con-
trols, stiffer springs are a must.
"Racing is hard on the clutch,"
Pro Circuit says. "You always do
[strengthen] clutch springs for
serious racing."
A new CNC-machined clutch
cover, made out of billet alumi-
num, was installed ($169.95) on
our bike; Pro Circuit says that
not only does it look better, but
it is stronger, less susceptible
to damage during a race, lighter
and disperses heat better.
More power also means that
more heat is being generated
deep within the motor, and ex-
cessive heat can rob power and
increase chances of engine fail-
ure. Another way to help combat
that problem Pro Circuit says is
to install its more efficient and
stronger silicone radiator-hose
kits ($84.95).
"Our radiator hoses have bet-
ter flow," says Pro Circuit. "The
stock hose has a Y design; we
have a one-piece unit which
gives it that better flow it needs.
Plus, the silicone material is bet-
ter suited than rubber to handle
hot temperatures."
The blue-colored hoses also
give the bike that cool look and—
heck ya!—that's important, too.
Speaking of the YZ's water-
cooling system, if there's one
weak area with the 2014 YZ250F
it's the water pump shaft, accord-
ing to Pro Circuit. It's prone to
failure. Yamaha has since updat-
ed the shaft with the 2015 model,
and that '15 shaft can be used to
replace the shaft in the '14 YZ like
