The donor engine for this build came
out of a 2010 Honda CRF450 dirt bike.
All of the electronics and fuel-injection
system came out of the bike, and the
rest was sold for parts. Spinning two
tires in the rear, the engine produces
just over 40 horsepower.
Although both of these quads are exotic, hand-built machines, it’s the most even
two-stroke-versus-four-stroke shootout we have ever done. They have nearly identical overall weight and horsepower readings.
It’s been a while since we have tested a two-stroke race machine this fast. The
500cc two-stroke powerplant fit nicely in the custom Walsh chassis. A compact,
polished FMF expansion chamber is a real eye-catcher.
GBC Bomb Squad tires provided plenty
of traction on both of these machines.
They were mounted up on Goldspeed
wheels. We raced with 18-inch tires in
33 foot-pounds of torque, while the
thumper has an even 30.
Both engines use a traditional
kick-starter, reducing the complica-
tions and weight of a battery and
extra wiring. The chassis weigh in at
375 pounds ready to race. The body-
work off of the LT-R is pretty much
the only bodywork that can facili-
tate the rearward-kicking start lever.
That might be one of the reasons
Suzuki made the original Quadzilla
chassis so long. The other reason
is because it was so powerful and
would flip over backward if stuffed
into the Quadracer 250 chassis. The
Suzuki engine was harder to kick over
when cold, but the Honda was harder
to start if you stalled it after warm-up.
Neither were noticeably hard to start.
The beauty of this build is that the
power Walsh ended up with was
strong but very linear. Other than the
sound, you didn’t feel like you were
riding a two-stroke. There wasn’t a
hard ramp-up of power or a pipey top
end. To achieve this, Duncan Racing
tuned the stock carburetor to work
well with the modern and open intake
design. On the exhaust side, Walsh
went with the most compact expan-
sion chamber they could find. The
end result was an FMF product that
grabbed attention from either side
but didn’t get in the way of the rider’s
feet or legs.