1965 Bultaco Sherpa S Scrambler – 3-Page Vintage Road Test Article

Description

1965 Bultaco Sherpa S Scrambler – 3-Page Vintage Road Test Article
Original, vintage magazine article
Page Size: Approx. 8″ x 11″ (21 cm x 28 cm) each page
Condition: Good
Twenty six horsepower in a 188 lb. package! This combination
will assure Bultaco its enviable reputation in scrambles cornpeli-
tion around the world. As one of the world’s most progressive
motorcycle manufacturers, the Spanish firm has gone all out to
combine tried and tested engineering methods with many new
design techniques. The result is an exceptionally fast, agile com-
petition bike.
There is no secret about the success of high power-to-weight
ratio competition machines. Four wheeled, as well as two wheeled
racers are almost always built as light in weight as possible with
as much power as can be “crammed in” without detracting from
the vehicle’s handling advantages.
Bullaco has attacked the power-to-weight problem from both
sides; Alloys are used extensively in the frame as well as in the
engine. Even the throttle twislgrip assembly is made of light alloy!
Engine weight has been minimized through the use of light metals,
too. Cylinder head and barrel are both featherweight. Frame
design is such that an absolute minimum of metal is used, but
extreme rigidity is retained through the skillful utilization of
strongly gusseted joints.
At the other end of the power-to-weight scale, the Sherpa S
really shines. No effort has been spared in creating an excep-
tionally high powered two-stroke. The ports are hand finished
and employ carefully studied design theory. Great thought has
gone into proper combinations of metals with respect to heat
expansions and clearances. Dyke ring Mahle pistons offer low
expansion, allowing closer piston clearance. 13:1 compression is
another factor behind the Sherpa’s strong punch. Perhaps it also
explains why a healthy kick is necessary to start the engine.
Bearing design has received its share of attention. Needle bearings
are used on the wrist pin while the big-end rod bearing is of
roller type. Another unique feature is the use of four flywheels;
one magneto flywheel, two full circle for the crankshaft, and an
inertia wheel. These guarantee a superbly balanced, smooth run-
ning engine.
The alloy cylinder has a replaceable hardened liner and double
ports — intake and exhaust. Bullaco claims to be the only two-
stroke employing webbed port design. Also unique is the use of
six head bolts. Seven bolts are used on the cylinder base. Precision
machined surfaces plus the careful selection of metals has en-
abled Bullaco to eliminate a head gasket. Ordinarily, a gasket
is necessary as a go-between for two different metals with varying
rates of expansion.
The exhaust port and pipe are huge! They look almost big
enough to stuff a fist into. As a critical pari of two-stroke design.
Bullaco has taken great measures to approach the ultimate in
exhaust flow, making full use of dynamometer tuning of the
system’s expansion chamber. The resulting exhaust note is shrill
and powerful sounding.
Carburetion is by a 27mm Amal Monobloc which is protected
from dirt by a washable element air cleaner.
All engine cases are fastened with Allen screws, a real blessing
to rider-tuners who have experienced the frustration of stripping
a Phillips-head screw.
HANDLING & PERFORMANCE
In the handling department the Sherpa S stands out as a
clearly “professional” type vehicle. Most outstanding to CYCLE
lest riders are the tight cornering characteristics. The wide fork
angle allows the rider to bend right down into a light arc without
feeling as if he’s about to “dump.” It should be especially easy
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