1974 Kawasaki 400 S3 - 5-Page Vintage Motorcycle Road Test Article

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1974 Kawasaki 400 S3 - 5-Page Vintage Motorcycle Road Test Article
Original, vintage magazine advertisement / article
Page Size: Approx. 8" x 11" (21 cm x 28 cm)
Condition: Good
...
When you've cleaned and set the points, you've done a job.
Oil injection pumps are the sine qua non of modern two-strokes.
Squared cylinder and head assemblies distinguish the 400; appearance reflects that of Yamaha RD 350.
larged to 57mm (from the S2’s 53mm) and
are fitted with 26mm carburetors—up 2mm
from those on the 350. Both of these changes
have added tone to the Kawasaki’s already-
impressive muscle, and a lot more class to its
appearance: the styling is all right; most of
the improvement is in terms of apparent
quality. At one time Kawasaki’s cylinders
were cobby enough to have been cast in box-
es of used kitty-litter, and we are delighted
to find all the old nubs and warts missing
from those on the 400.
Some of the performance gain inherent in
the displacement and carburetion revisions
probably is offset to some extent by the low-
ered compression ratio the engine gets with
its new cylinderheads. The old 350 triple
had a compression ratio of 7.3 to 1; in the
400 this has been dropped to 6.5 to 1. Per-
haps the reduction is intended to ease the
thermal stresses on the engine, and to make
it more tolerant of fuel quality. But it is
equally possible that this particular change
is directly linked to the redesigned kick-start
mechanism—which has resulted in a drasti-
cally different over all starter drive ratio
The S2’s kick-starter drive passed through
the gearbox and clutch, with gearing that
provided an extremely low effort level at the
pedal and a correspondingly low number of
crankshaft turns per kick. The 400’s starter
drive still runs through the gearbox, but now
the ratio raises the leg-muscle requirement
considerably—and translates a healthy kick
into a whirling frenzy at the crank.
No change has been made in the transmis-
sion ratios and that’s good because none was
needed. Like the 350 from which it is de-
rived, Kawasaki’s 400 pulls well over a fairly
broad rpm range but does fall flat below its
working powerband. So it needs a good
gearbox . . . and it has one. We think that
this new model has a slightly nicer gear se-
lector mechanism than that in the 350, and
we definitely like the relocation of neutral,
which now is between first and second gears
instead of being a notch past low gear. And
the limit for strain-free cruising has been
bumped upward a notch by switching from
the 35O’s 43-tooth rear wheel sprocket to
one having 41 teeth.
This alteration in the overall final drive
ratio, from 6.56 to 6.25 to 1 in fifth gear,
assumes special importance in light of the
new rubber-bushed engine mountings. With
rubber cushions inserted between engine and
frame very little vibration gets through to
the seat, pegs and handlebars al moderate
engine speeds. Unfortunately there exists a
point beyond which the combination of vi-
bration and reflected torque create loads the
rubber bushings cannot resist. Then the
slight freedom of movement provided by the
bushings actually begins to amplify engine
vibration. You’ll feel this in the handlebars
quite strongly just as the speedometer needle
sweeps past the 70 mph mark, and the effect
is present in more subdued form under hard
acceleration in the lower gears. Most people
will have the good sense to keep their cruis-
ing speed below 70 mph and won’t notice
the abrupt increase in vibration level, but if
the 400 had the 35O’s gearing the shaking
would commence at a lower speed and we’d
all learn to hate it. As things stand the rub-
ber bushings do help and the Kawasaki 400
S3 will impress nearly everyone as being a
very smooth-running motorcycle.
Along with the revised engine mounting
system, the 400 gets a new frame—or at
least a new frame part number. Frankly, we
can’t see any difference between it and the
35O’s frame. It may be that the difference is
confined to minor variations in brackets. Or,
perhaps Kawasaki uses thicker-wall tubing
in fabricating the frame for the S3 as a
means of regaining some of the rigidity lost
in rubber-mounting the engine—which no
longer can serve as a structural member.
Whatever Kawasaki may have done with
the frame, the steering head angle remains as
it was on the 350, and trail is increased from
4.3 to 4.4 inches only because the 400’s 3.25-
section front tire is slightly taller than the
S2’s 3.00-18. But with the “soft” engine
mountings the S3 chassis has been given
softer springs, and under most road condi-
tions the bike does nicely in getting past the
humps and hollows without jolting its rider.
The suspension’s single comfort-related
shortcoming is that it has that all-too-com-
mon inability to deal with sharp discontinui-
ties, however small, in the road surface. The
seams in poured-concrete roads especially
appear to totally overwhelm the forks.
The S3’s forks also are overwhelmed by
the effects of maximum-effort braking. We
have come to expect that disc brakes will
perform minor braking miracles, but the one
on the Kawasaki 400’s front wheel is an ex-
ceptionally good example of the type and it
dumps an enormous weight-transfer load on
the forks. The relationship between pressure
applied at the lever and retarding action at
the disc is so precise that you can get the tire
working right at the point of lockup without
worrying about inadvertently going past that
point. Only one difficulty intrudes: the brake
is better than the forks and stronger than the
fork springs, so that in a panic-level stop the
forks compress enough to use up nearly all
their travel and then the lack of damping
lets the front wheel hop, banging the forks
right against the stops. At the limit you get
the sound of forks clanging, and a pullulat-
ing squall from the front tire that evokes im-
ages of a basso profundo toy poodle in hot,
noisy and glorious pursuit.
After you’ve made a few of those full-ef-
fort stops you may discover, as did our test-
ers, that the front disc has begun to squeal.
And that’s the only distress signal we got
during a session of brake brutalizing.
There’s a tendency for the rear brake’s ped-
al-travel to lengthen somewhat as the drum
gels hot but this seems to be no more than a
temporary condition and never seriously im-
pairs the triple’s ability to stop.
Handling is a category in which those
comfort-oriented spring rates are very much
a mixed blessing. Though the 350 S2 was
one of the best handling machines we tested
in 1972, it was a bit chattery in choppy
turns. The S3’s softer springs have banished
that tendency to chatter—at a price. You get
slightly better tire adhesion with the 400,
but the new springs let it sag lower in re-
sponse to cornering loads and it loses some
of the S2’s generous cornering clearance.
Then too, the Kawasaki's dampers are a tri-
fle limp, allowing the bike to surge up and
down on its springs. Consequently the han-
dling becomes distinctly rubbery and the
steering imprecise when you get into a situa-
tion that calls for a lot of improvising in the
middle of a comer. Actually, the worst thing
about the 400’s overall handling characteris-
tics is that they do not inspire a sporting
rider’s confidence. Under nearly all condi-
tions the S3 behaves very well and its ride-
quality is better than that of the 350. But
when you begin hustling it lets you know
that it is not totally forbearing; that if
pressed beyond its limit it might turn upon
you with tooth and claw.
Riding comfort is made up of more than
soft springs. Some bikes ride well enough
but simply do not feel right; others feel fine
for the first five minutes in the saddle and
then begin pinching nerves and numbing
muscles all over one's body. The Kawasaki
feels right all the way, with the kind of nice,
natural placement of pegs and bars that
wears very well on a long trip. Some back-
sides may be too wide for the seat, which is a
little narrow, but what the seat lacks in
width it compensates with length and pad-
ding. A wider seat probably wouldn't be any
more comfortable for most riders, and
would look funny on this narrow motorcy-...
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