A milled head, extra base gasket and a Vertex piston was all
C4MX did to make the YZ250 purr.
The Kayaba SSS suspension is the best on the market and
was made even better with Enzo revalving the front and rear.
OTHER UPGRADES: It took the efforts of a host
of aftermarket companies to morph the YZ250 into a
full-fledged race bike. Rock River mounted up ODI bars
and grips, along with ARC levers. Dubya provided Excel
A60 rims mated to Dunlop tires and an oversized Galfer
front brake rotor. A Works Connection Pro Launch start
device was installed, along with a Guts Racing ultra-light
Phantom Zero Gravity seat. The stock footpegs were
replaced with Torc1’s wide-platform Voltage footpegs.
WHAT DID WE REALLY THINK?
One of the Yamaha YZ250’s greatest attributes is that
it has been refined over a 10-year period. When Yamaha
found a problem, they fixed it; however, Yamaha did not
mess much with the overall package. If it worked, they
left it alone. The result is one of the best race bikes on
the planet. An Amateur rider can roll it off the showroom
floor and take it directly to a race. It’s that good. But
racing on an AMA National track is asking a lot from
a stock bike. That is where Rock River stepped in to
elevate the YZ250’s game. There is nothing they did that
you can’t do to your Yamaha YZ250, regardless of its
age. We liked where the money was spent. ;
The new Powercore 2.1 FMF silencer is longer than the
typical two-stroke silencer, but performs better than ever.