This is mostly the doing of Mitch Payton
and the Pro Circuit race team, of course.
The only other bike that might surpass
the record of the KX250F is, interestingly enough, the KX125.
All those trophies were already
on the shelf when the 2017 model
arrived. This particular bike comes
after what might be considered a
drought in Kawasaki’s reign of success. Since 2014 it’s conceded most
pro motocross wins to Yamaha. So,
this new bike carries the whole KX250F
legacy. That’s pressure.
Last year the stock KX250F was the heaviest bike in the class. Most of the other makes received
major attention, while the KX was completely unchanged.
Accordingly, weight loss was a major focus. The engine
has entirely new cases and castings, and it was slightly
reshaped along the way. The cylinder was re-angled by 7
degrees to give the intake a straighter flow into the combustion chamber. As in the past, the intake has two injectors: one in the throttle body and another up closer to the
airbox. The whole intake is new, all the way back to the
airbox, and the throttle body is smaller, simpler and lighter
this year, even though it’s still a 44mm Keihin. Kawasaki’s
ignition still uses a system of three couplers that can be
replaced to change the power characteristics. There’s
also a handheld FI calibration kit available for more extensive changes.
The head is new. The exhaust cam has more lift and
the piston is lighter. The cam chain and its sprocket have
lost weight. Below, the flywheel is lighter and the rod has
a new plain bearing on the bottom. The transmission is
mostly unchanged, aside from new shift forks and added
needle bearings on the shift shaft.
The KX uses a
The frame itself is the most changed of all. The bike is
1.3 inches narrower across the radiator shrouds and lost
0.25-inch across the main spars, as well as 90 grams
of weight. Beyond just being lighter and narrower, the
frame has different flex characteristics. Remember the
stories about that first aluminum frame on the 1997 Honda
CR250R? It was so stiff the suspension felt harsh. Since
then, Kawasaki and other companies have spent a great
deal of time with computer
modeling to analyze and
control where and how
much a frame flexes. The
steering head, shock
mount and swingarm
mount have all
been revised with
this in mind. The
(Left) In the engine department it has received new exhaust
cams, a lighter pistion and a new head. (Right) You might not
think the motor looks any different, but all the castings are
new for 2017. The cases, head, piston and intake tracts have
all been rethought.
gave the new
KX250F the same
treatment that the
KX450F got last
year. The frame and
bodywork are slim-
mer, and the bike
lost 8 pounds.
MX TEST: 2017 KAWASAKI KX250F 78