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By: Jason Giacchino
Email:
offthepegs@atvsource.com
October 2006
Saying Goodbye to the
Two-Stroke
 As I’m sure many of you are already aware,
the 2007 ATV model year will witness the absence
of several long running models. Most notable of
course is the Yamaha Banshee, the liquid cooled
350cc twin cylinder two-stroke that has been
kicking up roost around the world since 1987.
The crackdown on two strokes is nothing new, in
fact since 1997 California has stopped issuing
green stickers for any two stroke recreational
vehicle and allowed only units designed for
closed circuit competition to be sold in the
state. Now here it is exactly a decade after
that decision and the nationwide kiss of death
for the two-stroke is eminent.
While news of the two-stroke’s demise may not
be all that shocking, the success of the
technology that replaces it is a bit more
noteworthy. Knowing, just as we the consumers
did, that the reign of the two-stroke was nearly
at an end; the manufacturers kicked four-stroke
development into high gear during the mid to
late portion of the last decade. While many
doubted the heavier, slower revving four-stroke
plant could step in and take over where the
wild, hard hitting two-strokes left off, the
transition has been fairly effortless. In fact
creative engineering and industry-wide
rejuvenation have resulted in the development of
true to life performance four-strokes. Best of
all industry insiders believe the bar will
continue to be raised in upcoming model years.
As an added bonus the manufacturers themselves
have returned some long overdue attention to the
sport of ATV competition; support that has been
lacking since the late 1980's.
Yamaha, Honda, and Suzuki have wasted no time
in producing race-worthy equipment while
Kawasaki is putting the finishing touches on
their own entry in the
viable new 450 class.
What is interesting is that history tends to
repeat itself and this is not the first time
we’ve witnessed Kawasaki coming late to the race
track. Two decades ago Honda was campaigning its
250R successfully, Suzuki had its Quad Racer
250, and Yamaha birthed the Banshee, but
Kawasaki’s performance 250 remained unseen. It
wasn’t until April of 1987 that the green
machine finally hit the scene in the form of the Tecate 4. Short lived hardly defines the
Tecate’s hold on the market; a mere two years
after it was introduced, Kawasaki dropped the
Tecate 4 from their line altogether. Honda and
Suzuki held out a bit longer but ultimately
bailed out on the premier 250cc class
performance ATVs as well leaving only Yamaha to
carry the two stroke torch right on through the
1990's.
While the remaining manufacturers turned
their attention to the utility market throughout
most of the 1990's, Yamaha held steady with its
Banshee- producing the sand shredding beast year
after year. The later models received a handful
of updates, most notable being the switch from
J-Arm to A-Arm suspension in 1991. In a time
when class action law suits threatened the
entire concept of performance ATVs, Yamaha never
flinched.
So with a success story like the Banshee’s,
why then is 2006 the final year of its US
existence? In a word: pollution. The flaw in the
two-stroke design from the onset (which dates
all the way back to 1860) is that its combustion
cycle takes place so rapidly that intake and
exhaust flow often mix. Not only does this
increase the rate of fuel consumption, it
releases additional unburned hydrocarbons into
the air. It was never a case of if but when in
discussing the doom of the two-stroke motor. The
manufacturers had only two options in front of
them: To create a more efficient burning
two-stroke or scrap the two altogether and focus
on the more environmentally friendly
four-stroke. While a more efficient (cleaner
burning) two-stroke design would have bought the
manufactures more time, they wisely skipped the
intermediate step and dove directly into the
technology intended to last the test of time.
So here we are just shy of two decades after
the Banshee’s introduction, on the cusp of
retiring a good friend to the history books.
Although a sad affair, the excitement of the
designs on the horizon offers ATV enthusiasts
much to be excited about.
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