2018 YAMAHA YZ450F
1. Electric starting has been added
to the 2018 Yamaha YZ450F. The starter motor is behind the cylinder and is
powered by a lithium-iron phosphate
battery that weighs just 1.5 pounds. A
kickstarter kit will be offered.
2. The new YZ450F engine’s power
delivery is focused on ease of use at
lower rpm and more power on top.
Thanks to a straighter intake angle,
higher-lift cams, increased valve-tim-
ing overlap ( 8 degrees), increased
compression ( 12.8:1) and a 12mm-lon-
ger and 3mm-smaller-in-diameter head
pipe, the power should be moved
down into the powerband.
3. Mechanically, the engine gets a
new bridge-box piston that is 6 grams
lighter (thanks to a 2.3mm-thinner
dome thickness). The piston pin is
4. The 44mm fuel-injection throttle
body is no longer a Keihin but instead
a Mikuni. To help it produce power,
there is a longer spark-plug electrode,
new ECU mapping and a redesigned
5. The crankshaft assembly is coun-
tered by a more effective balancer
and more crankshaft inertia; however,
inertia from the flywheel has been
6. The clutch gets a new pressure
plate, durability coatings on the steel
drive plates, treatments and smooth-er-operating springs.
7. In the transmission, second, third
and fourth gears are 1mm wider.
8. The twin-spar aluminum frame’s
main spars are now extruded rather
than hydroformed. The brace pipe
below the steering head is now
forged. Frame rigidity has increased
25 percent vertically, 9 percent hor-