VOLUME 56 ISSUE 40 OCTOBER 8, 2019 P89
The new head also features
steeper valve angles for an
even straighter downdraft in-
take power port. Cam profiles
are also more aggressive.
Also, the connecting rod has
been lengthened 1.5mm to re-
duce side loads on the piston.
Delving deeper into the
engine, you'll find a new
condenser, a now one-piece
rectifier/regulator, a tweaked
air filter with improved seal-
ing, and an updated exhaust
pipe with a larger-diameter
head pipe.
The ECU mapping has
been re-calibrated, and there
is now, like the YZ250F de-
buted last year, a two-position
map switch on the handle-
bar that allows you to make
changes mid-moto without
having to pull over. Yamaha
has also updated its smart-
phone power-tuner app.
In the five-speed gearbox,
the gear drive dog heights are
slightly taller for increased dura-
bility and more accurate shifts.
In the chassis department,
Yamaha went through the
YZ's bilateral beam aluminum
frame with a fine-tooth comb
in search of that perfect blend
of flex and rigidity to give
the rider the best possible
feel, comfort and control on
the track. They tried many
combinations and finally
settled on one where the
thickness of the mainframe
spar is reduced by a scant
0.5mm, and the lower cradle
tube thickness is increased
by the same amount, 0.5mm.
(Right) The YZ450F
might not be the
lightest bike in its
class, but it sure
feels like it is on the
track. (Top right)
Please, give everyone
in Yamaha's style
department a
standing ovation.
