TOGETHER AGAIN FOR THE FIRST TIME
Last year the KTM got a new motor and frame. KTM
was on a mission to find and eliminate excess weight. The
motor remained a single-overhead-cam, four-valve, electric-start five-speed, but it was made more compact in all
dimensions and got a new throttle body and EFI system.
The bodywork, the linkage and the frame were all new and
all lighter. The WP 4CS fork, on the other hand, saw only
a few changes, as it has each year since it was first introduced in 2013.
When the smoke cleared, the 2016 KTM 450SX-F was
the fastest and lightest 450cc MX bike on the market, and
it was the only one with electric start. It was an amazing
feat. The only reason it didn’t take over the world was the
fork. The 4CS was basically an off-road fork that had been
modified and recast as a motocross fork. Then, at the midyear point, KTM came out with a limited run of Factory
Editions that tipped the company’s hand for 2017. The WP
AER 48 was standard up front. This was an air fork that
shared virtually nothing with the old 4CS. New game.
Now the 2017 450SX-F has an even newer version of
the AER 48 fork, plus an interesting list of other changes. The bike now features what KTM calls traction control, which can be activated through a handlebar switch.
This isn’t the existing “launch control” that is designed
to be used only for the start; it’s an embedded program
designed to prevent excess wheelspin throughout an entire
race. It isn’t traction control as defined by the AMA Pro
Racing rulebook, which prohibits traction control that compares front-wheel speed and rear-wheel speed. The KTM
uses no wheel sensors.
The rear suspension valving and spring are new and
designed to work with the new fork. The top triple clamp
is different, and the handlebar clamps feature a separated lower clamp and bridge-type upper clamp for more
torsional stiffness. The rear brake pedal is 10mm longer,
and less aggressive brake pads are used. The aluminum
head stays are 60 grams lighter than the steel ones they
At the risk of reporting news that isn’t news at all, the
KTM motor is an absolute beast. Aside from the Husky
450, which shares the exact same motor, it was the most
powerful motocross bike of 2016 by a significant margin.
Unless there are unreported surprises still coming, it will
be the most powerful motor of 2017. It wins in low-rpm
torque, in the midrange and on top. The fact that the
motor is so powerful throughout the rpm range is what
makes it manageable. If the power were all on top, it
would take a Dungey-level training program just to hang
on. But, the KTM builds predictably to a climax in the mid-
9000-rpm range, which is very high for a 450. The long,
smooth power delivery makes it easy to upshift early if
your arms can’t take it.
Apparently, the people at KTM
understand that this kind of
horsepower might feel good
in the short run, but it’s a
little demanding over the
course of a long race.
The new handlebar
MX TEST: 2017 KTM 450SX-F