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2009 Yamaha
ATV Models Dealer Show Report
All New YFZ450R Sport ATV Revealed
Also new on the Yamaha YFZ450R is the addition of
the fuel injected engine. The engine includes an
all new 5-valve titanium head, all new cases, new
gear ratios and a new crank shaft. The throttle
body has been increased to 42mm over the previous
39mm, which helps eliminate bogging. The EFI system
has automatic idle control and automatically adjusts
to temperature and altitude.
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The
YFZ450R has an all-new engine based on the
2008 YZ450 engine and fuel injection with
a 42mm Mikuni throttle body
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The new engine design also incorporates a new
cylinder head design that increases bottom end
power while maintaining that same mid range hit
the YFZ is famous for. This also helps to make
the power band smoother, which helps to decrease
rider fatigue.
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#94 Dustin Nelson won the 2007 Yamaha /
ITP Quadcross Championship on the YFZ450,
and for 2008, he is racing both Quadcross
& the WORCS Series |
Although the power is a little smoother on the
new YFZ450R, the throttle response has been improved
while the amount of effort has been decreased
in order to reduce “throttle thumb”.
“The throttle response on this thing is
amazing!” said Dustin Nelson. “You
can punch the throttle and it will not bog or
stall. The effort you have to put into the throttle
is better also. The difference between the old
YFZ and the new model is huge on how much easier
the throttle effort is.”
One of the best known modifications that most
YFZ riders have done in the past is the notorious
“cam mod” where the exhaust cam is
retarded one tooth in order to give the engine
more top end and give it the same timing as the
YZ engine. In previous models the exhaust timing
was set the same as the WR engine at 109. This
modification is no longer necessary as the exhaust
timing is now set at 105, the same as what is
found in the YZ engines and With the intake port
changes made to the new engine, the bottom and
mid range power has also been increased. All new
engine cases have been designed to be stronger
to help increase durability and reliability not
only in stock machines but also if the owner decides
to do any engine modifications.
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YFZ450R
Fully Adjustable KYB Shocks Front &
Shocks with Kashima coating
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One of the biggest differences between the current
YFZ450 model and the new YFZ450R is the front-end
suspension components. The new model incorporates
a wider stance, upgraded shocks, and a one-inch
longer rake. Nelson stressed that the improvements
made really helps with the handling, especially
in its ability to reduce bump steer. “I’m
looking forward to trying the new front end in
the WORCS races. In some of the knarly down-hills
and turns that get really rough is where I think
the increased rake will really help us out,”
said Nelson.
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