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hile Yamaha en joys gett ing most of the cred it for start ing the
four-stro ke revolution in motocross. it appears that it does-
n't want any credit for pe rhaps helping to kill off th e tw ost ro ke. So for 200S , Yamaha annou nce d that it has no inten tions of dropping its yz two-stroke line up anytime soon and
has instead com plete ly redesigned its YZ I25 and 2S0 tw o- str oke s. Its goal? To go
afte r t he four-strokes.
24
JUNE 30, 2004 • C YCLE N EWS
In order to do that,
weight. So Yamaha went all out to lighten up Its YZ two-st rokes (and to gIve
them more power, of course.) Amazingly, Y
amaha claims th e new YZ 125 is
about 10 pounds lighter than last year's 125, and the new YZ250 is about e ight
pou nds lighter than its predecessor. To he lp do th is, Yamaha sw itched to aluminum fra mes for its two-strokes.
As Honda found out when it first went to the aluminum frame, the lighte r
metal is e xt re mely rigid and can result in a harsh ride . But Yamaha says th at it
o vercame th is obstacle by incorpo rati ng a new approach to construction. Most
of the frame is cast aluminum, wh ile certain pieces are forged or extruded . By
doing this it wa s able to contro l the rigidity of t he fram e by how t he various
pieces w ere made . Y aha claims the ne w alu minu m frame retains the sa me
am
characterist ics of the old steel frame while saving weight and incre asing
st rengt h.
T he frame was t he mo st extensive change t hat t he 250 received : how ever,
40th Anniversary
