Offroad: When we weren’t racing motocross on our YZ250FX, we
took it out in the boonies for some rock bashing.
This is how we set up our 2015 Yamaha
YZ250FX for track and trail. We offer these settings to help steer you in the right direction.
KAYABA SSS FORK SETTINGS
Most MXA test riders stayed close to the
stock clicker settings (after we added 10cc of oil
to each fork leg), with the faster riders going in
four clicks. Our slower and Vet test riders loved
the softer feel of the YZ250FX forks and thought
that they would be good enough to race with
in stock trim on everything but a jump track.
There is a risk of bottoming when you drop
three spring rates and lighten the low-speed
For hardcore racing, we recommend this fork
setup for the 2015 Yamaha YZ250FX (stock
specs are in parentheses):
Spring rate: 4.4Nm
Oil quantity: 345cc (335cc)
Compression: 11 clicks out
Rebound: 11 clicks out
Fork leg height: 5mm up
Notes: Most of the fork’s internal components
are exactly the same as the YZ250 forks;
however, the fork-valve shim spec is stacked
much differently and the springs are 27mm
shorter and three rates less compared to the
YZ250F’s ( 4.4Nm to 4.7Nm). There is less
low-speed compression and rebound damping
for a plusher feel, especially over small bumps.
The high-speed compression has been increased
for more bottoming control.
KAYABA SSS SHOCK SETTINGS
Our most noticeable shock change was the
108mm of race sag. We did this to lower the
rear of the chassis to help balance out the
handling issues caused by the Yamaha engineers
raising the rear of the chassis to accommodate
For hardcore racing, we recommend this
shock setup for the 2015 Yamaha YZ250FX
(stock specs are in parentheses):
Spring rate: 56.0 Nm
Race sag: 108mm (90mm to 100mm)
Hi-compression: 1-1/2 turns out
Lo-compression: 10 clicks out
Rebound: 11 clicks out
Notes: The shock body is the same as on
the YZ250F, however, the eye-to-eye length is
4mm longer (462.5mm to 458.5mm) and the
stroke is 6mm shorter (128mm to 132mm). Rear-wheel travel is 15mm less for more fender space
to make room for the battery (and the seat is
raised up 15mm). As for the damping, the shim
stack is different than on the YZ250F, but the
spring rate is the same. Compression damping is
more progressive because of the shorter shock
stroke, while the rebound damping has less low
speed and more high speed. ❏
including cold weather. The battery in a KTM is 1 pound
lighter. Any aftermarket iron-phosphate battery could save a
couple of pounds.
( 6) Tires. The stock Dunlop AT- 81 tires are good offroad
tires, but there are better motocross choices.
( 7) Dzus fasteners. We love the idea of Dzus fasteners on
the airbox cover but hate the execution. Remove the D-rings or
cover the side-mounted ones with tape. Your pants will thank
you for it.
( 8) Seat height. Although the seat height is a bad deal for
an offroad bike, it is what the jacked-up rear end does to the
frame geometry that rung the most alarm bells. The tall rear
end creates a stinkbug stance and steeper-than-optimum
Q: WHAT DO WE LIKE?
A: The like list:
(1) Engine. Mechanically, it is identical to the YZ250F
engine but detuned for offroad riding.
( 2) Suspension. Mechanically, the suspension components
are the Kayaba SSS units from the YZ250F but softer.
( 3) GYTR Power Tuner. If you want to get the most out of
the YZ250FX engine, do yourself a favor and invest in a GYTR
Power Tuner, or borrow one from a friend for five minutes.
( 4) Clutch. The clutch pull is amazingly light, which Yamaha
achieved by going from eight plates to nine, which allowed
them to use softer clutch springs.
( 5) Electric start. Watts up, baby.
( 6) The bike itself. It’s been a long time since the Big Four
made an offroad bike this good.
Q: WHAT DO WE REALLY THINK?
A: There was simple logic in MXA’s approach to the 2015
Yamaha YZ250FX. We loved the offroad capabilities of the FX
but wanted to skew it further in the direction of motocross.
We didn’t, however, want to turn it into a full-blown motocross
bike, because the YZ250F already exists (and is a better race
bike by virtue of its lighter weight and more appropriate
powerband). We also didn’t want to break the bank, throw
the baby out with the bath water or ruin a good thing. So, we
made minimal changes and loved the results. But, for most test
riders, the jacked-up rear of the bike was a downer.