The Yamaha YZ450F’s old-school front brake isn’t even a
contender in the pucker-power derby.
Thanks to the mapping changes, the YZ450F is smoother,
more manageable and exhibits gentlemanly manners.
Years ago, Yamaha’s head test engineer, Ed Scheidler,
let the MXA wrecking crew test seven different head
stays on a YZ250. The bike felt like a different machine
with just a head-stay change.
The new steel motor mounts will retrofit on last year’s
Q: FOURTH, WHY WOULD YAMAHA MAKE
THE GEARING TALLER?
A: Yamaha is employing a trick that Honda used
back in the old CR500 two-stroke days. When consumers
complained that the CR500 was too powerful, Honda
didn’t detune the engine; the engineers just added a
smaller rear sprocket to mellow out the delivery. The
CR500 power became more manageable because it had
to pull a taller gear out of each corner, which translated
into better throttle control, slower revs and the ability to
stay in one gear longer.
Yamaha did the same thing with the 2015 Yamaha
YZ450F by going from a 49-tooth rear sprocket to a
Yamaha is employing band-aid tactics, because in our
opinion it made a major mistake with the 2014 gearbox,
although Yamaha meant to do a good thing. In 2014,
Yamaha decided to close up the big gap between
second and third gear that racers had complained about
for years. But, instead of raising second gear closer to
third, the engineers lowered third gear. Unfortunately,
they also changed the primary gear ratio to move all of
the gears up. This was a bad move, because while they
made the changes to close the gap between second and
third gear, the result was a wider gap between third and
fourth. To fix this flaw, Yamaha changed from its
traditional 48-tooth rear sprocket to a lower 49-tooth
sprocket (to allow the 2014 gearbox to mimic the 2013’s
To recap, in 2014 they moved the wrong gear down,
then raised all the gears up, which created a big gap
between the gear they moved down and the gear above
it, forcing them to lower the gearing at the rear sprocket
to get back to where they were in 2013. Now, they have
raised the overall gearing by going to a taller 48-tooth
sprocket in place of last year’s 49.
This comedy of gearbox errors resulted in a mellower
power delivery for 2015, thanks to taller overall gearing.
And, the mellower powerband helps the YZ450F’s turning
prowess, especially from tip-in to center-out.
The MXA test riders weren’t sold on the gear ratios but
did like the effect on the chassis. Unfortunately, there is a
serious loss of drive in the middle gears that can only be
retrieved by serious hop-up dollars or a 49--tooth sprocket..
Q: IS THE 2015 YZ450F FASTER THAN THE
A: No, but it is smoother than the 2014 YZ450F, and
that makes it easier to go fast on. From gear to gear, the
2014 had more thrust, largely due to the lower gearing and
more aggressive mapping, but don’t shed a tear for the
YZ450F’s powerband. No need. The YZ450F is the most
powerful 450 on the track. It pumps out close to 59
horsepower in stock trim, and an aftermarket pipe will
easily push it over 60 horses.
This is usable power from bottom to top, made all the
more usable by the map and gearing mods. And, of course,
it can be made faster with a different map and gearing