(1) Engine. The most obvious change is that the
cylinder is now rearward slanting, with the exhaust ports
facing where the carburetor used to be. There’s also the
four-valve layout, narrower valve angle, high-lift camshafts,
shorter and lighter single-ring piston, smaller crankshaft,
offset cylinder and a more efficient oiling system.
( 2) Electronic fuel injection. It took Yamaha six
years, but the Keihin FCR carburetor is now extinct in
the four-stroke market. The YZ250F was the last holdout.
Yamaha finally appeased consumers by using a 44mm
Keihin throttle body with a 10-hole injector and high-pressure battery-less electric pump to deliver fuel to the
engine. No more jetting. No more guesswork. As a result,
the ignition can be customized with the GYTR Power
( 3) Chassis. Every part of the chassis is new, including
the engine brackets and oddly shaped subframe. Note
that the dimensions of the steering head, rake and trail
are the same as the 2013 model, but the flex characteristics are different. Yamaha’s engineers focused heavily
on improving the centralization of mass by moving the
weight (muffler, gas tank and engine) closer to the middle
of the YZ250F. They succeeded.
( 4) Suspension. The YZ250F still comes with Kayaba’s
SSS (Speed Sensitive System) suspension, but the spring
rates have been stiffened and the damping changed
for more ride control. The front axle diameter has been
increased by 2mm for greater rigidity, and the inner fork
tubes have undergone a new polishing process for
greater sheen and less stiction.
( 5) Styling. You’d have to be blind in order to miss
the radically changed body styling on the YZ250F. From
the air intake ducts to the embedded graphics to hidden
gas cap under the seat, the YZ250F is unlike any of its
predecessors. It’s worth mentioning that every plastic
piece on the YZ250F can be shared with the YZ450F.
Q: WHY DID YAMAHA DROP-KICK THE
KEIHIN FCR CARBURETOR?
A: To be blunt, Yamaha ditched the carburetor
because of you. Yes, we’re talking to you; that is unless
you’re a two-stroke diehard, in which case you wouldn’t
be reading this bike test anyway. Back to the question
at hand. Electronic Fuel Injection (EFI) has become the
standard fuel delivery system on all major four-strokes.
Perhaps you’ll remember that the 2008 Suzuki RM-Z450
was the first bike to come out of the crate with EFI.
That was six years ago, which equates to a millennium
when it comes to technological advancements.
Yamaha had been testing EFI for years before finally
pulling the trigger for 2014. In fact, the 2010 YZ250F was
very close to receiving fuel injection, but at the eleventh
hour their engineers pulled the plug. Why? It came down
to a lack of performance. To quote a Yamaha representative, “Electronic Fuel Injection made an improvement [on
the older models], but it wasn’t revolutionarily better. So,
2014 YZ250F 2014 Yamaha YZ250F: For years the MXA wrecking crew has
wished for an all-new
YZ250F. Our prayers
were finally answered,
and we’re glad that
we waited. It’s a much