Q: FIRST AND FOREMOST, IS THE 2016
YAMAHA YZ250F BETTER THAN THE 2015 YZ250F?
A: Better is a qualitative measurement that has many
facets. As for the 2016 YZ250F, its performance is about the
same, but, on a technological level, it is improved.
Q: HOW MANY CHANGES WERE MADE TO THE
2016 YAMAHA YZ250F?
A: We didn’t expect any changes, given that the
YZ250F was new from the ground up in 2014. But, Yamaha
targeted durability, rider comfort, engine performance and
(1) Piston. The piston has been changed to a sturdier
bridge-box design with a flatter top and new fuel tumble in
the combustion chamber, but the 13.5:1 compression ratio
remains the same. The thinner-wall-diameter piston pin is
now DLC coated, and the angle of the oil mister under the
piston has been changed to help cool the top-end bearing
by 50 degrees. Overall piston weight has been reduced 7
percent, while the wrist pin is 18 percent lighter (thanks to
a 9.4mm hollow core instead of last year’s 8mm hole). The
piston and pin combined are 18 grams lighter.
( 2) Crankshaft. A new crankshaft and counter
balancer have been “re-timed” to help reduce vibration at
high rpm. This was achieved by moving the weight of the
crank halves towards the center while reducing weight
farther out on the crank circles. Crank weight itself is
increased 13. 9 grams. As for the counter balancer, the
pendulum weight has been moved from 180 degrees before
top dead center (TDC) to 228 degrees (TDC). Additionally,
the tolerance on the big-end crank pin has been changed to
grip the crank halves 20 percent tighter than in 2015. This
increases crank rigidity at high rpm. Molybdenum-coated
bronze thrust washers have been placed on each side of the
connecting rod to reduce friction (the connecting rod itself
has undergone a new heat-treatment process for increased
strength). The thrust washers are even dimpled to help
( 3) Clutch. The clutch hub has a smoother and flatter
surface area to provide better contact with the clutch plates.
Yamaha’s engineers removed last year’s judder springs from
the nine-plate clutch pack. The judder springs preloaded the
clutch pack but did nothing for bite.
( 4) Shifting. Yamaha made three changes to the shift
system on the 2016 YZ250F. First, the neutral detent on the
shift drum was reduced in width to make it less likely that
the YZ250F will hit neutral in motion. Second, the engagement corners of the dogs on third, fourth and fifth gears
were reshaped to insure more positive engagement. Finally,
the shift stopper design was changed for the third time in
three years. Originally, the shift stopper interacted with the
shift detent wheel via a bearing-equipped roller; however,
the bearing had the poor taste to disintegrate, so Yamaha