For some time we have been receiving
reports from Japan that the Bridge-
stone factory has set up a handful of scram-
blers based on their Sport 90. Always, the
reports have been glowing, sprinkled with
such adjectives as “near-unbeatable,” “un-
believable," and so-on, but since one is
constantly besieged with rumors in this
business, one simply wails until there is
conclusive proof that the stories have sub-
stance.
In this instance, the reports appear to
be accurate and a limited number of
Bridgestone 90 Scramblers now in the U.S.
promise to make under-lOOcc racing pretty
lively in the months to come.
The claimed 8.8 bhp of the Bridgestone
Sport 90 has been increased to 12 bhp
(claimed) for the Bridgestone 90 Scram-
bler. This gain has been attained by in-
creasing (he opening duration of the rotary
valve 10 degrees; modifying the cylinder
transfer porting; increasing the size of the
carburetor from 17mm to 18mm; raising
the compression ratio to 10:1; advancing
ignition timing to 23 degrees btc; adding
an expansion chamber: and replacing the
alternator with a constant-loss ignition
system.
But the "mods" don’t end here. The
scrambler is fitted with a small, but com-
fortable seat (despite its lack of padding),
high, reinforced bars, a modified top fork
bridge, a smaller gas tank, an alloy front
fender, Class C-type 2.75 x 17-inch tires,
folding pegs and a number plate. The tool
chest is eliminated, as are the center stand
and lighting gear (of course). The side
stand has been retained and its attendant
"weight penalty” is easily offset by the
convenience of not having to scout for a
rock, a box or a tailgate to support the
bike when it is inactive.
The rear fender has been neatly pared,
and while a pound or so has probably
thus been eliminated, we rather imagine
that this change has been made in the in-
terest of appearance.
Suspension on the Bridgestone 90
Scrambler is quite stiff — surprisingly so.
The manufacturer feels that the machine
is sufficiently versatile to be used in just
about any type of dirt surface competition,
but the ride would be difficult to take for
very long periods over really rough ter-
rain. Standing position is not too bad for
a rider a bit shorter than average, and it’s
likely that the bike will have its greatest
appeal to this size person. Therefore, no
quarrel. The Scrambler handles slowly;
that is. it isn't quick to cross up and this
is particularly good for a light machine
with so much power. Even with the heav-
iest of the staffers aboard, the Bridge-
stone would send up a nice, steady stream
of track on its way out of a turn with the
power on. The bike must be pushed down
hard into a turn to cross it up, and after...