Perhaps you read our compre- hensive 2015 “MXA 250 Four- Stroke Shootout” in the January
2015 issue. If you did, then you’ll recall
that the Yamaha YZ250F topped the
class, followed closely by the Kawasaki
KX250F. Those two bikes were head
and shoulders above the rest of the field;
however, those results were determined
by real-world testing, done by a plethora of riders at tracks around California.
If numbers are more your thing, then
this special feature is for you. MXA
pitted the six 250 four-strokes against
one another on the dyno. If horsepower
findings determined the winner, there
would be a three-way tie for top honors.
Fortunately, that’s not how the MXA
wrecking crew works. Still, we
uncovered some very real truths about
the 2015 class of 250 four-strokes thanks
to a day at the dyno.
WHAT DO THE NUMBERS MEAN?
The following information is based on
dyno runs of the six major 250cc four-stroke motocross bikes of 2015. All the
bikes were dyno’ed on the same day,
on the same dyno and with the same
operator. This was done to ensure that
the results weren’t skewed by outside
factors that would benefit or hinder any
one bike. Note that if red flags were
raised about a series of numbers, we
dyno’ed a second version of that bike to
cross-reference the numbers.
Motocross riders are not robots. Sure,
horsepower numbers are fascinating,
but they don’t tell the whole story. Very
few among us ride at 13,000 rpm. While
things like peak horsepower are interesting, having the fastest bike on the track
doesn’t amount to a hill of beans if you
can’t ride it. After all, a 43-horsepower
engine and a dollar will buy you a cup
We provide peak horsepower numbers
in our 250 four-stroke horsepower analysis, but we also isolated the horsepower
ratings at 8000 rpm, 10,000 rpm and
12,000 rpm to get a graphic display of
what the powerbands look like. While
we were at it, we also graphed peak
horsepower, peak torque and, most
important, we measured the width of the
rpm range where each bike topped 40
horsepower (as a measure of the breadth
of the bike’s most usable powerband).
Numbers don’t lie. Or do they?