BEFORE THE BORE: KTM’s 2012 250SX-F is like nothing
in its class. It started life as an off-road bike in 2011 and was
brought into the MX world as the only electric-start 250F
available. The starter and battery resulted in a weight penalty—the KTM was almost 10 pounds heavier than any of the
other bikes. An even bigger problem was the power output.
The KTM still ran like an off-road bike, with slow revs and
unsensational peak output. It was an impressive bike in many
ways, but it wasn’t a great motocrosser.
THE PARTS: All the Cylinder Works big-bore kits that we
used in this shootout make use of an 80mm piston. That
gave the KTM a nice little bonus. It started off with a
76.0mm by 54.8mm configuration, so the 80mm piston
represented a bigger increase, percentage-wise. The
KTM’s final displacement was 275.5cc. As on the other
double-overhead-cam machines, we installed two Hot
Cams Stage 2 cams.
Most recent KTMs have two different ignition maps in their
electronic brains. We ran the aggressive map from 2011
along with a Moto Tassinari Air4orce intake boot and a
Factory 4.1 RCT Ti muffler with a Megabomb header. Since
one of the real issues facing the KTM is weight, we couldn’t
walk away without shaving off at least a couple of pounds.
CV4 makes a lithium-ion battery that does just that.
RESULTS: We achieved a completely unintended result
The 2012 KTM has kind of an off-road bike
feel that gets magnified with the 270 kit.
More current for the
FIFTH PLACE: KTM 275SX-F
KTM has the only electric-start 250F motocross bike. That’s
good, but the weight penalty isn’t. Race Tech handled the
KTM’s suspension duties.
with the KTM 275: we built an incredible off-road bike. It
gained power everywhere, but the best part was way down
low. Again, this isn’t necessarily anything you would notice
on the motocross track, but it made the bike much easier on
the trail. The KTM still has a comparatively slow-revving
motor, and that makes it feel sleepy on the track. It’s interesting to note that for next year KTM has a new 250SX-F motor
with a different bore-and-stoke configuration. Instead of having the longest stroke in the class, it will have the shortest.
This bike will still be available in the XC-W version, and you
can rest assured that many of those will become 275s. ;