cooled, four stroke, transverse four cylinders, DOHC, 2 valves per
Bore x Stroke
x 55.8 mm
4x 32mm Mikuni BS carbs
49 hp 35.8 kW @ 9000 rpm
Nm @ 7500 rpm
Speed / chain
Swinging arm fork with hydraulic shock absorbers.
275mm discs 1 piston calipers
Single 275mm disc
Traditions take time to build. Before 1969, real
motorcycles had a pair of cylinders—arranged in a V or side-by-side, take your
pick. Real motorcycles had push-rods, kick starting, drum brakes and 36-spoke
wheels, and until 1969 motorcycles were virtually tradition-bound to use these
items. It took one four-cylinder machine (the Honda 750) to depart from the
tradition and begin a new one. In the 10 years since 1969, multi-cylinder
roadsters have become the norm.
The Suzuki GS550EN is in the mainstream of the
1970s tradition. With its transverse four-cylinder engine, four carburetors,
dual-overhead camshafts, disc brakes and cast wheels, the GS is—to many of
today's motorcyclists—the epitome of what a modern motorcycle should be. To be
sure, the 550 has several completely conventional (some would say obsolete)
features whose designs pre-date 1969. For example, the Suzuki has only two
valves per cylinder, a breaker-points ignition system and an oil/spring fork
when it could have CDI, four-valve heads and air-assisted suspension. But,
regardless of the few up-to-the-minute designs it lacks, overall the GS offers
in one neat package the basic designs which are generally considered 1970s
It's easy to forget that the GS is also part of
another tradition: the 550EN is a variant of the standard GS550N. For many years
and for some pretty good economic reasons manufacturers have offered variants.
It's been a sensible way, for instance, to produce two different displacement
machines, each using the same chassis. Just a few years ago the manufacturers
grew more inventive and began concocting slightly different and slightly more
expensive models with ostensibly functional variations, such as four-into-one
Suzuki in particular has taken a practical and
economical approach to the production of functional variants. The EN has just a
few trendy modifications—cast wheels, a rear disc brake and a stepped seat—which
raise the cost of the EN to only $190 more than the standard N, but still give
it the customized look. Suzuki's use of stylish and inexpensive variations has
been commercially successful: last year the E models outsold the standard
versions in all four displacement categories where they were offered-400, 550,
750 and 1000cc.
Suzuki first introduced the GS550B in the spring
of 1977, about six months after the debut of the GS750, their first four-stroke
motorcycle. The 550's powerplant was a well-engineered, technically pedestrian
unit. There's been one engine refinement in the intervening two model years: to
cut down on gear whine, the original GS-B's straight-cut primary gears have been
replaced by bevel-cut cogs, and its 93-tooth/47-tooth gear pair has been reduced
to an 87/44 combination.
For 1979, the GS550's engine design can now be
considered even more straightforward in relation to some recently introduced
unorthodox 500/550cc machines such as the Honda CX500. The middleweight class
currently consists of two parallel twins (the Laverda 500 and the Yamaha 650),
three V-twins (the Honda CX500, the Moto Guzzi V-50 and the Moto Morini 500),
one opposed twin (the BMW R65), one single (the Yamaha 500) and four
four-cylinder bikes (the Benelli 500, the Honda and Kawasaki 650s and the Suzuki
550). Traditional transverse fours are outnumbered by twins of all engine
configurations, and that possibly foreshadows the building of a 1980s tradition.
Regardless of what the future holds, the GS-EN's
engine is currently one of the most reliable units around. A one-piece cast
cylinder head houses hemispherical combustion chambers with two valves per
cylinder. Adjustment of the valves is a simple matter of installing shims of
different thicknesses in the tappet tops. The dual overhead camshafts ride on
the head's plain bearing surfaces, and the shafts are driven by a roller chain.
With a nearly square bore and stroke of 56.0 x 55.8 millimeters, the GS
displaces 549cc and has a willingness to rev high.
Suzuki engineers have chosen to use roller
bearings at several points in the engine's bottom end where they might otherwise
have used plain bearings. Though roller bearings offer no advantage in
reliability over plain bearings and are actually a little noisier during
operation, they do require less engine oil pressure. Six caged roller and ball
bearings support the pressed-together crankshaft.
The number four cylinder's inside crank wheel
doubles as the primary gear, and there's bearing support just inside of that
gear. All four of the one-piece connecting rods ride on roller bearings at the
big end, and the slightly domed pistons ride on the rods' small ends' plain
bearing surfaces. Since the GS engine is a well-constructed representative of
the four-cylinder genre, it is expected that the 550 should be as smooth as
glass. It is up to a point, and that point is 5800 rpm. For a reason which is
peculiar to this engine, the 550 emits a very noticeable and irritating
high-frequency resonance from just under 6000 rpm until redline. The vibration
discourages the rider from high-rpm running for more than about 10 minutes at a
time; in the lower rpm range the GS vibrates minimally and is very comfortable.
Fortunately, around-town cruising and short
highway jaunts are most usually accomplished at speeds below the resonance
level. But canyon berserkos note that in third gear the 500 spins 6400 rpm at an
indicated 55 miles per hour (and that's definitely in the Shake, Rattle and Roll
zone). At 55 miles per hour in fourth, fifth or sixth gear, the engine is
comfortable, turning 5400, 4900 and 4500 rpm. However, the GS's powerplant, like
most medium-displacement engines, needs high revs to develop any serious
horsepower. The Suzuki produces 27.51 horsepower at 6000 rpm, and the rider
needs to chase the engine to 8500 to use its peak of 41.55 horsepower.
Historically, it's been the rare middleweight
motorcycle which has used a six-speed transmission; the only two currently thus
equipped are the Laverda 500 and the GS550. A six-speed gearbox has one primary
advantage over a five-speed: it lets the rider keep the engine in its powerband
easily. With the GS's horsepower married to vibration, though, the rider is not
encouraged to use the gearbox to advantage, and the six speeds are instead
occasionally something of a nuisance. For about the first 1000 miles of
operation gear engagement is rather stiff, and neutral is difficult to locate
except when the bike is standing still and the engine is idling. After the
initial break-in period the gearbox loosens up and shifts just fine.
Power to the gearbox is transmitted via a
15-plate clutch with a primary ratio of 1.977:1. When the engine is cold the
clutch works pretty well, with easy lever actuation and a wide engagement
spread. When the engine heats up, though, or when the rider abuses the clutch
with some uphill starts, the engagement point becomes narrow and actuation
Four 22mm Mikuni carburetors form the primary
part of the GS's induction system. To meet increasingly stringent Environmental
Protection Agency emissions standards, the carbs have been jetted somewhat
lean—which produces some flat spots in the 550's carburetion, especially in the
lower rpm range. The Mikunis' choke lever helps the GS start on cold mornings;
it's needed whenever the bike sits for more than half an hour, even in 60 degree
A non-mechanical ignition system is a trendy item
conspicuously absent on the stylish EN. The GS's breaker points setup in fact
performs at least as well as a CDI system, except for the fact that points need
periodic maintenance whereas the CDI rarely if ever needs adjustment. The GS
uses two sets of points mounted outside of the left crankWheel, and the ignition
fires two plugs every 180 degrees of crank rotation. A 12-volt battery, dual
coils and three-phase AC generator complete the GS's electrical system.
All of the GS-series motorcycles reflect a
commitment by Suzuki to give their bikes stout, rigid chassis. The 550's mild
steel frame uses 1.12-inch tubing for its main members. The heavily gusseted
steering head produces a 29-degree rake and 4.72 inches of trail. Both the
rigidity of the frame and its geometry result in excellent handling. At high
speeds especially the GS maintains its composure: there's no frame flex you can
feel, and very little wobbling overall. The GS's longish 56.5-inch wheelbase
produces good straight-line stability, and that attribute makes the 500 a much
better than average middleweight touring bike. Around town the 550 is a quick
and willing handler, and the bike is easy to throw around.
Designers of the GS emphasized strength over
light weight in the swing arm also. The mild steel tubular assembly has 1.5-inch
outside-diameter arms and moderately heavy gusseting at all the crucial points.
Because of its hefty construction the 550 is not exactly the lightest
middleweight available. Full of gas, the GS weighs 476 pounds, compared to the
469-pound Honda 650 and the 417-pound Laverda 500.
In the area of suspension the GS is falling
behind technologically. The GS1000, with its air/spring fork and shocks with
adjustable damping, is the best-handling one-liter machine available. Obviously,
Suzuki has the technology to design first-rate suspension units, but they have
elected not to use it on the middleweight GS. Instead, the 500 uses an
oil-damped steel spring fork, which is perfectly competent but not exceptional
in any particular area. Damping action is slow over bumps of all sizes, and the
resulting initial impression is that the fork is over-sprung. In fact, the
springing is about spot-on for a 170-pound rider; the fork regularly uses much
of its available travel over larger bumps and potholes. Though the suspension is
constantly working over small road irregularities (indicating that Suzuki
engineers have addressed the problem of stiction), there's still a lack of
cushiness. The fork gets the job done, and nothing more.
Nor do the shocks reflect the latest in
suspension technology. The absorbers are oil-damped and have five adjustable
spring preload settings. On the firm preload setting, the shocks perform
acceptably for fast riding on twisty roads. The stiffer springing reduces shock
travel, keeps the GS from wallowing and helps maintain needed ground clearance
during hard cornering. On the lighter spring preload settings the GS tends to
pogo when ridden hard, but yields a more comfortable ride on the open road.
Shock compression and rebound damping is light, and that lets the shocks react
quickly to bumps; it also encourages the bike's rocking-horse motions when the
preload is on soft.
During hard cornering on a tight road there are
several chassis components which touch down. In a moderately hard turn, or when
the shock springs haven't been jacked up, the centerstand is sure to drag. After
that, during very hard turns, the footpegs, side stand and header-pipe brackets
all scrape lightly at about the same time.
At about the same time that the chassis
components begin wearing grooves in the highway, the Bridgestone tires,
especially the rear, begin to drift. The slippage is controllable, progressive
and slow; it's primarily a polite reminder that the GS is cornering nearly as
hard as it can. To its credit, the GS maintains its stability while any parts
drag, or while the tires slip.
Both wheel assemblies walk the line between
function and style. The cast wheels are indeed heavier than spoke units, but
(aside from being better-looking) they're also more rigid. That rigidity goes a
long way to aid cornering stability by helping to eliminate wheel flex.
Moreover, the cast wheels don't need maintenance.
Both disc brakes provide excellent stopping
power. The two-piece riveted disc found on the original GS-B was replaced in
1978 by the one-piece item currently in use on the GS-EN. There's very little
chatter when the rider activates the 550's front brake, even though there is a
pattern which resembles heavy chatter marks on the disc itself. Regardless of
any idiosyncrasy, the brake performs very well: it activates progressively and
resists locking even during panic-stop situations.
The GS's feel belies its categorization as a
middleweight; it feels nearly as big as the average 750. The seat is roomy and
allows two-up riding comfortably. Medium-density foam is used in the seat and
it's good for a reasonably numb-free long ride. The handlebar is swept back very
little, and it positions the rider naturally forward into the wind. Judging by
the handlebar cant, we'd say that Suzuki does not anticipate too many owners
attaching fairings. Folding footpegs are new for 1979, and they too are mounted
in the right spot for non-faired cruising.
Most of the 550's detail components, such as its
various gauges and switches, petcock, fork lock and choke lever, are
well-engineered and functional. For touring riders the '79 GS has a cluster of
terminals located under the seat to accept some electrical accessories, so
owners need no longer cut and splice wires to attach their CB radio or tape
deck. New for this year is a starter interlock, a safety feature which requires
the rider to pull in the clutch lever while starting the engine. The interlock
switch is identical to the one which activates the brake light when the front
brake is used. Touring riders had been complaining that the GS-B and C handgrips
were not long enough to allow the convenient installation of mechanical
cruise-control devices. The GS-N's hand-grips have been lengthened slightly to
cure this minor annoyance.
Just a few of the 550's detail items need
refinement. There's only one helmet lock, and the seat must be lifted to get at
it. The fuel tank's locking cover, which is at best minimally effective at
keeping out thieves or vandals, is flimsy and a hassle to re-lock. Both
rubber-mounted mirrors vibrate vigorously above 5000 rpm. Removing the
intermediary sections of the mirrors' shafts—the portions which contain the
rubber—neither increases nor decreases the severity of the blurring.
Though the four-cylinder GS is smack in the
middle of the 1970s tradition, it's in danger of becoming dated. The things it
does well, it does very well. It's fast, it's comfortable both in town (because
of its nimbleness) and on the highway (because of its roominess), it's
absolutely stone reliable and it's inexpensive compared to any of its
middleweight rivals. But if the GS is going to carry the banner of the
Transverse Four into the 1980s, it's going to need some refinement to keep it
up-to-date and competitive. That nagging problem of high-rpm vibration has to be
exorcised. And some other 500/550s, notably the CX500, offer better suspension
compliance. Still, for this year, traditionalists who are bound and determined
to buy a four-cylinder middleweight could do a lot worse than the Suzuki 550.
It's a perfectly competent 1970s motorcycle.
Sure, the LN's stylistic variations intrude on
the 550's functional ability, but that hasn't hurt the Low Slinger's success.
Preliminary sales figures indicate that the LN is outselling both the standard
550N and the EN. Which only goes to show that a lot of riders prefer Summer
Nights on the Boulevard to gassing it through the canyons.
Responding to the market impulses for that
high-bar, low-light, step-seat, long-fork, short-muffler look, Suzuki has
introduced a set of machines for the Raked-out Randys of motorcycling. Early in
1979, the GS550LN, as well as the GS750LN and GS1000LN, appeared, a sure sign
that Yamaha's discovery would not be Suzuki's loss.
To their credit, the Japanese do not produce
specials by snapping on cosmetic body work and hoping for the best. In the case
of the GS550LN, suspension modifications abound. The new leading-axle fork
carries three-rate fork springs which are different from those found on the
EN-model. The preload portion is the same as the EN, but the middle rate is
lighter, and the last portion stiffer than the EN. To complement the softer
springing, Suzuki has lightened up the rebound damping. The shocks have the same
springs and stroke as the EN, but the preload position has been shortened from
23.5mm to 6.0 millimeters, so the L-model has less preload on the springs,
making the laid-back 550 feel softer in back, as well as in front, when compared
to the standard Suzuki 550s. The wheelbase of the 550LN is almost two inches
longer than the normal 550s; and despite appearances, the LN has less rake then
the E- or EN-models (28 versus 29 degrees) and slightly less trail (4.6 versus
There are at least three changes that current LN-
and EN-models share. First, closer tolerances have been maintained in
carburetion production to hold emissions within ever-tightening EPA standards.
Second, early in 1978 the 550's primary gears were changed from straight-cut to
bevel gears in order to make the engine quieter; and third, at the same time the
primary ratio was altered slightly, from 93/47 (1.978) to 87/44 (1.977).
Other than these changes, the LN differs from the
EN only in cosmetics. This face and body treatment includes the special fork, a
six-inch quartz-iodine headlight, high-rise handlebar, pulled-back gas tank,
short mufflers, stepped-seat and grab-handle. Perhaps the most obvious thing
about the restyle is the tank, which rides a considerable distance back from the
steering neck. Viewed from the sides, the open space between tank and neck is
covered by molded and pleated plastic panels that hide the steering neck/ frame
tube junctures and parts of the wiring harness. These panels hint that Suzuki
hurried into production with the LN-models.
The LN doesn't function as well as the EN. While
the LN rides more softly than the standard-type 550, the suspension does nothing
to keep the cow-horn handlebar from tweaking the rider's right wrist inward.
After a half-hour, the rider notices wrist-strain. Depending on your height and
proportions, the step in the seat may be in exactly the wrong spot. The basic
riding position which the LN Suzuki requires does not encourage brisk riding.
Hard-riding enthusiasts accustomed to standard bikes will simply feel awkWard
and out-of-place on the GS550LN. They'll conclude that the LN is a
boutique-motorcycle, best suited to boulevard nights.
And they'll be right.
Source Cycle Guide 1979