development program. Not only can
the New Zealander ride a motorcycle
but he also knows what he’s talking
about when it comes to developing
one. He helped develop the frame,
suspension, slimmer ergos and lower,
flatter seat to give the rider more feel,
particularly in the front-end.WHY IS IT FAST?
One thing I have come to know over the
years dealing with the guys at Yamaha
and spending time with them, is that
they love to win. They are racers and
they want to come first. The guys at
Yamaha Australia have a good
relationship with the factory in Japan
and the feedback that comes from our
country, as well as the feedback from
our good friends over the ditch like
Coppins, is taken into account to
producethemostsatisfyingmotorcycle
thattheycan.Yamahapeoplearenot
followers,theyhaveneverbeenabout
that.Theyhavealwaystriedtobeatthe
forefrontofdevelopmentandaren’t
afraidtotakealeapintothe
unorthodoxtotryandfindanew
directionintothefuture.
WhatI’mtryingtoleadintohereis
thatthe 2019 YZ250Fisarevolutionary
bike.Itfollowsnotrendsandnordoesit
copyitsdesign.Itisabikethatis
runningitsownraceandsettingthe
standardforthosethatfollow.
Thereverse-headenginehasbeen
somethingthatYamahahasbeen
stickingwithandcontinuingtodevelop
since 2014 withthe250F.Thecylinder-
headbeingreversedmeansthatthe
airboxismounteduphighoutofthe
dustandthethrottlebodycanbe
angledstraightdowntotheintake
valves.Thisconceptgivesthe
straightestpathfortheair/fuelmixture
toenterthecylinder.
Someraceteamswithotherbikesare
actuallyre-anglingtheintakeportsto
createmorepowerbutthiscomeswith
theYamahaasstandard.
Toaccommodatetherearexhaust
port,theheaderpipeloopsright
aroundthecylinderbeforemeetingthe
silencer.Therearetwobenefitstothis.
Oneisthatitcreatesextralengthin
theheaderpipewhichhelpscreate
torqueandtheotheristhatisallows
forthesilencertobelocatedcloserto
thecentreofthebike.TECH TALK I 2019 YAMAHA YZ250F
Monoshock delivers 317mm travel at the wheel Breather hose coming out of cover is weirdWrap-around header boosts bottom-end torqueThe compression ratio is now a
substantial 14.8:1 and the smoother
ports and new valve train mean there
is a much higher and smoother flow
rate through the cylinder.
This is where all the power of the
YZ250F comes from and the light
crankshaft means that it can safely rev
to 14,000rpm.
The aluminium bilateral beam frame
has been designed to be rigid enough to
perform well under pressure while still
being able to flex under control without
compromising the bike’s handling and
still be smooth under the rider.
The suspension can be looked at as
being either outdated or class-leading. It
depends on your point of view.
Personally, I don’t care that the KYB
Speed Sensitive spring-cartridge fork
was designed and developed over 10
years ago because it is still my favourite
and I don’t believe anybody has been
able to better it.
When somebody comes up with a
suspension package that works better
then I’ll be happy to admit the KYB is
dated but, until then, I am of the
opinion that it is class-leading.
The suspension is designed to work
well with the compact chassis and
keep the bike balanced well. The goal
of Yamaha for 2019 was to improve the
feel at the front so it worked hard with
the suspension settings and chassis
design to do so.76 | MAY 2019 http://www.adbmag.com.au