Our unique WImaha Power
Valve System constantly adjusts
exhaust port timing, improving
poweroutput over the entire
rpm range and holding blow-by
to a mit!imum so that combustiot!
efficiency is greatly itzcreased.
Introducing the onlymotocross
bikes that come willi two engines.
The two-stroke engine is almost perfect
for motocross. Its lightweight, compact, powerful and easy to cool.
No\v, about the "almose'
Wth the typical two-stroke engine you have
to set the exhaust timing for one oftwo things:
low-end torque or high-end speed. Or, find a
happy medium and lose a little on both ends.
As you might expect, weve got a new
approach.
Our newYFVS on the YZ125 and YZ250.
YFVS translates into Yamaha Power
Valve System. And that translates into getting
two engines in one. One set for torque, the
other for speed.
TheheartofYFVS
is a cylindrical valve
thats incorporated
into the exhaust port.
The valve is cut to
match the shape of the
