Suzuki
GT125 Road Test
 
Motorcyclist Illustrated Dec 1977
There cannot be many motorcyclists who commute
to work each day at a steady 9000rpm, but this
is the rather rare experience that faces owners
of the Suzuki GT125 who wish to keep up with
the traffic on dual carriageways and motorways.
For at 9000rpm this perky little two-stroke
twin is singing along at 70mph, with another
l000rpm in hand before reaching the red line.
One of the outstanding attributes of the GT125
is its ability to deliver this kind of performance
for mile after mile without overheating ok
showing the slightest sign of power loss. It
will maintain the legal limit unstintingly on
a level road and exceed it by at least 5mph
in favourable conditions, but naturally a steep
gradient usually requires changing down from
fifth to third gear to preserve momentum.
Cruising at this sort of speed the Suzuki is
commendably smooth, the only vibration being
felt as a tingle through the footrests which
is definitely present but never bothersome.
The tank, seat, and handlebar are free from
the malady, and the rubber-mounted mirrors stay
clear also. The mechanical noise is low for
a two-stroke, helped perhaps by the cast aluminium
Ram Air shroud over the cylinder head. Initially
the combined induction roar and exhaust noise
was noticeable, but the exhaust emits one of
the more pleasant two-stroke sounds and is nowhere
near as pronounced as the wail emanating from
its 250cc brother.
The price you pay for this level of performance
is heavy fuel consumption. The average for the
test was 40mpg — the same as the Suzuki
GT250, the Honda Gold
Wing and CB750 K7. Throughout the test I rode
the machine close to its performance limit,
because this was the only way to keep to my
time schedules. It was also the most fun and
the Suzuki thrived on this treatment. Riders
who are not prepared to accept this sort of
fuel consumption would be advised to steer clear
of the GT125, because it would be pointless
spending money on a high-performance machine
in its class and then pottering around everywhere
in a bid to conserve fuel. If it's economy you're
after you would be far better advised to buy
one of the four-strokes or the smaller step-throughs.
The main drawback of the high petrol consumption,
other than the sheer cost, is that the machine's
2.2 gallon petrol tank will take you a mere
75 miles before you need to start searching
out a petrol station. The Suzuki went 12 miles
on reserve before I stopped to replenish its
tank, which took exactly two gallons to fill
to the brim. If the manufacturer's tank capacity
claim is correct that means reserve will take
you no more than 20 miles before leaving you
stranded. The Suzuki is not alone in having
too small a tank, but an extra half gallon at
least would be welcome - preferably a gallon.
The other reason for the high fuel consumption
is the quite amazing acceleration offered b/
this 2531b lightweight. Power starts to come
in at around 4000rpm. It climbs gradually to
6000 where it grows stronger. By 7000rpm the
bike starts to wail and goes hurtling forward
with incredible rapidity for a 125, with the
power rising progressively to 9500 and falling
off imperceptibly thereafter. Between 7000 and
l0,000rpm the GT125 must be one of the quickest
machines around under 200cc, and the bewitching
effect of its acceleration in this area is such
that I could hardly resist using the revs freely.
This characteristic makes the little Suzuki
great fun to ride, and it will have even greater
appeal to riders who don't have my 14 stone
carcass to lug around.
One of the equally appealing traits of the
GT125 is that, unlike its 250cc stablemate,
it can be eased away from a standstill on a
gentle throttle without having to be kept within
a narrow power band, and therefore I would consider
it a suitable machine for beginners. It has
the benefit of lower initial cost than most
250s, and lower insurance rates, yet is able
to deliver usable performance as the novice
becomes more proficient. And if the rider has
his sights set on bigger machinery, then he
can look forward to passing the test on the
125 and move on to greater things, skipping
the expensive 250 class entirely.
The engine is a straightforward four-port two-stroke
twin, producing 16bhp at 9500rpm and 9.4 ft-lbs
of torque at 9000rpm. The five gears are driven
through a wet multiplate clutch and are ideally
spaced. No matter what the situation there is
always a correct gear to cope, and the changes
are smooth, silent and positive. Actual top
speed is 75mph at l0,000rpm, with 78mph indicated
on the speedometer; at an indicated 60mph the
true speed is 56.2mph. The motor is willing
to rev beyond 10,000 in top gear on hills, but
this will only contribute to more rapid component
wear and possible damage. Oil is metered to
the engine by the successful Suzuki CCI injection
system, which is reasonably economical at 200
miles to a pint of two-stroke lube.
Starting was always a single-kick task, hot
or cold and the carb-mounted choke could be
dispensed with quickly after firing. The twin-coil
ignition proved reliable and the test bike never
lost its tune despite prolonged hard use. Clutch
lever action is featherlight, and the light
steering makes for easy manoeuvrability in traffic.
Far more surprising is the Suzuki's excellent
straightline stability right up to its top speed.
Roadholding is very good and the suspension
copes well with fast, smooth bends. On bumpy
backroads, however, the handling was much less
precise but still enabled spirited riding in
relative safety. The lurching and wallowing
I experienced on bumpy bends may have been due
largely to my weight, but the frame certainly
seems well able to handle the power the engine
puts out
A single downtube from the steering head is
welded to a duplex cradle running beneath the
motor to meet the swinging arm. Three tubes
run back from the top of the steering head,
the main one bending down to tie up with the
swinging arm pivot, the other two continuing
back to form the top part of the triangulated
rear subframe. It looks good and works well.
Coupled with adequate ground clearance this
allows the GT125 to be thrown about with ease,
although I have my doubts about the suitability
of the Inoue tyres. They never felt quite right,
yet even in wet weather they held the road and
showed no signs of imminent breakaway.
Inspiring less confidence are the brakes. They
work well in dry weather, but in the wet that
hydraulic front disc suffers from an unacceptable
delayed action. A sticker on the fork leg warns
riders of this well-known trait, but all the
stickers in the world are no substitute for
some serious and much-needed'development of
brake pad materials. As mentioned in my Gold
Wing test, work by the Transport and Road Research
Laboratory indicates that pad material may have
more bearing on this wet braking problem than
actual disc material, as hitherto assumed. Whatever
the cause, remember that in wet weather the
first two seconds of front brake application
bring no results while the pads dry out; after
that the brake works normally - until the next
time.
Lighting on the GT125 is surprisingly good
for such a small unit, and both beams give a
useful spread of light. The tail light is very
large and bright and the indicators are easily
visible in daylight.
Instrumentation is simple, and thankfully we
are spared Suzuki's digital gear indicator on
this model. The matching speedometer and revcounter
are well-lit, and the speedo contains a trip
odometer while the neutral, high beam, and indicator
warning lights are housed in the tachometer.
The small 12y battery, main electrical connections
and a spare fuse live behind the right snap-on
sidepanel. The oil tank and tool tray are easily
accessible under the hinged and lockable dualseat,
which incorporates a helmet lock and the petrol
tank is quickly detachable for easy access to
the ignition coils. The air filter element is
easy to reach from the left side of the engine,
and the machine boasts a simple steering lock
that requires a minimum of fumbling.
The saddle is reasonably comfortable, but a
pillion rider might soon tire of the constant
rise and fall of the rear footrests, mounted
directly on the swinging arm. While we are discussing
that general area of the machine, I fail to
appreciate why Suzuki cannot fit a full chain
enclosure. The present chain guard simply does
not keep chain oil off the rear of the bike
and after a few hundred miles this can detract
greatly from the otherwise neat appearance.
The standard of finish is good, however, and
both paint and chrome look durable.
The GT125 boasts an excellent . horn for a
motorcycle of this, capacity, and the large
rear light is an added safety bonus. All the
more pity, therefore, that the brake light is
operated only by the rear brake; there is provision
for a front brake light to be fitted but, like
the 250 and 400cc Suzukis, none is. It would
offer an important safety boost, and this would
more than outweigh the small extra cost involved.
Cost, again, is probably the reason why the
automatic vacuum fuel taps fitted to most larger
Suzukis are absent from the GT125. The manual
tap fitted to the test machine was stiff and
therefore awkward Jo use.
In town the Suzuki's light steering and short
wheelbase make it an ideal choice for threading
through tiresome snarl-ups, and that extra
urge from the motor at 7000rpm is especi- ally
useful for passing slower traffic as quickly
and safely as possible on a 125. And when it
come to parking, the machine's light weight
takes the effort out of using the centre stand,
while a side stand is fitted to meet the needs
of the really lazy.
Suzuki's GT125 will set you back £460,
serving as a horrifying reminder of what inflation
is doing to the price of even small motorcycles.
But it still represents good value, and slightly
undercuts the competition: Yamaha's RD125 is
listed at £475 and Honda's new CB125T
at £489. Model for model, Suzuki appear
to have a policy of pricing their machines just
below those of their rivals, and this certainly
seems to pay off, judging by the popularity
of the smafler models especially. But the GT125
gives more than simple value for money —
it adds a tinge of the performance and excitement
of larger bikes to the commuter class. Young
riders looking for a replacement for that cast-off
moped would be wise to consider seriously a
quick 125 such as this Suzuki before rushing
off to spend almost half as much again on a
250.
Suzuki GT125 Specifications;
- Engine: Two-stroke four-port
with Ram Air cooling Displacement: 124cc Bore
and stroke: 43 x 43mm
- Lubrication: Suzuki CCI
- Oil tank capacity: 2.1
pints (1.2 litres)
- Transmission: Five-speed
constant mesh
- Maximum power: 16 bhp at
9500rpm
- Maximum torque: 9.4 ft-lbs
at 9000rpm
- Fuel tank capacity: 2.2
gals (10 litres)
- Fuel consumption: 40mpg
average on 2 star
- Oil consumption: 200mpp
- Overall length: 75.2in
- Width: 30.3in
- Overall height: 41.9in
- Ground clearance: 5.Sin
- Suspension: Telescopic
oil-damped fork front; oil-damped five-way-adjustable
shocks rear
- Tyres: 3.00 x 18 rear Inoue
2.75x18 front
- Dry weight: 2381bs
- Starting: Kickstart only
- Top speed: 75mph at 10,000rpm
(maximum safe revs)
- Speedometer error: True
56.2mph at indicated 60mph
- Colours: Red, candy gold,
metallic blue
- Final drive: Exposed unlubricated
chain
- Brakes: Single-leading-shoe
drum rear; single hydraulic disc front
- Ignition: 12v battery and
twin coils
- Frame: Single-downtube
tubular cradle-type
- Price new: £460
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