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Triumph Bonneville 750 T140E

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Make Model |
Triumph Bonneville 750 T140E |
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Year |
1979 |
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Engine |
Air cooled, four stroke, parallel twin
cylinder,
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Capacity |
744 |
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Bore x Stroke |
76 x 82 mm |
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Compression Ratio |
7.9:1 |
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Induction |
2x 30mm Amal carb |
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Ignition /
Starting |
- / electric |
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Max Power |
54 hp @ 6200 rpm |
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Max Torque |
41.8 ft-lb @ 5500 rpm |
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Transmission /
Drive |
5 Speed / chain |
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Front Suspension |
Telescopic forks |
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Rear Suspension |
Girling shocks 3-way spring preload, |
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Front Brakes |
Single 254mm disc |
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Rear Brakes |
Single 254mm disc |
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Front Tyre |
3.25-19 |
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Rear Tyre |
4.00-18 |
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Dry-Weight |
200 kg |
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Fuel Capacity |
18.2 Litres |
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Consumption average |
51 mp/g |
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Top Speed |
118 mp/h |

Road Test 1978
The Triumph Bonneville has traditionally been
held responsible for everything from keeping Harleys out of winner's circles to
keeping small-town daughters locked up. But nowadays a new kind of fantasy
surrounds the well-known curves of the Bonnie—the fantasy of a machine from an
earlier, simpler age. And even if those over 25 can hardly consider the Fabulous
Fifties an age of simplicity, whenever the conversation turns to Triumphs the
talk inevitably turns nostalgic.
It's too bad. The Bonneville is more than a
cartoon of a Fonz-bike, more than simply an oil-leaking hunk of prehistoric
British iron. It is as legitimate a motorcycle as can be found anywhere, one
whose character is instantly apparent in the bluff honesty of its upright
cylinders, and one which deserves the attention of all serious riders,
allegations of outrageous anachronism notwithstanding.
But so overwhelming is the flood of techno
marvels from Japan that most enthusiasts probably think that even this latest
Bonnie is simply the old one dolled up in new powder and paint. No so: In the
biggest single change since the bike got its 747cc engine in 1970, the Amal
concentric carburetors have been chucked out, to be replaced with a pair of far
more modern Amal Mk IIs. Mikuni-like, they eliminate much of the hassle of the
old Bonnies, since they have a single lever-type choke and excellent flow
characteristics enhanced by parallel intake tracts. Other changes include the
use of "inverted" Girling gas shocks, Dunlop K81/ TT100 tires front and rear (in
place of the old squarish K70s) and redesigned side covers.
The list price is one of the few things that
hasn't changed much. The improvements and inflation in the two years since we
last tested a Bonneville have only raised the price $300, to $2299.
Given that price, the potential buyer might well
ask (since it's remarkably low for a 750) what he gets, besides a conversation
piece. As our test Bonneville showed me all over again, quite a lot.
First there's the phenomenal Triumph handling, a
thing so unique it's been a cornering yardstick used by motojournalists for over
a decade. Indeed, it's that very familiarity with the Bonneville's handling
that's bred a certain contempt for it, especially among Triumph marque freaks,
who maintain that the post-'71 bike was never as good as the "old" Bonnie. So
it's probably worthwhile to examine the roots of the whole thing.
What makes Bonneville handling so special
today—in the era of monsterbikes—is its effortless precision. This is a
motorcycle whose pegs your grandmother could drag, not because they're too low
(and they are, a bit) but because the bike combines magic qualities of
suspension geometry, frame stiffness and mass placement in such a way that no
steering input seems to require much effort. This is something we tested further
than normal, since we replaced the standard handlebar—an egregious cryptochopper
affair totally incongruous among the clean lines of the bike—with an optional
($16) European handlebar with which all domestic Triumphs are equipped. And
riding efforts with either bar were precisely the same: so low you only need
think the bike through a corner.
This spectacular ability of the Bonneville to
dazzle its rider with instant response is matched by the road-holding of its
suspension and tires. Dunlop's H-rated (130-mph) K81s have a justly-won
reputation for stickiness that finds a perfect match in the compliant front fork
and firmly sprung rear shocks. Although the Girling folks claim about a half
inch less travel with the new gas emulsion shocks than with the old air/oil
types, the damping is superb, and we simply left the shocks on the softest of
their three spring-preload positions—even for two-up riding.
There are only two limiting factors in how far
and how hard you can ride the Bonneville: the dragging point of the
undercarriage and the fatigue imposed by the mild but ever-present vibration of
the big twin. The first factor is something all Triumphs within recent memory
have shared, and the culprits are easily identifiable: the huge, rubber-booted
footpegs, the left-side stands and right-side exhaust pipe. Mind you, it's not
like you ground these items when turning into the supermarket parking lot; you
have to be trying for the limit with some energy before the pavement rushes up
to the unyielding bits. And even when the bike thunks gently onto the ground
with one of its appendages, the fantastic stability of the Bonneville allows the
rider either to simply ignore the peeling rubber and trailing sparks or back
off—all without necessitating a change in line. Or, for that matter, a rise in
the adrenaline level.
Similarly, the loping thunder of the vertical
twin (muffled but still satisfyingly present even with the too-long exhaust
pipes) finds its way into the handlebar and footpegs in the form of a gentle
throb. This is not the feared and often invoked Eyeball Death Rattle used to
scare young riders away from British bikes, but an insistent reminder that the
motorcycle you're astride is a product of the technology of three decades ago,
when engine counterbalancers were quite simply not to be thought of—especially
in motorcycle engines. But it doesn't require a hopeless Anglophile to recognize
that the vibration is low-frequency and only intense enough to rate about a
three on the Vibro-Scale (on which the Yamaha XS Eleven is a zero and the BSA
Victor is as close to ten as anyone can bear).
Nonetheless, despite the excellent ergonomics of
the bike—footpegs, grips and controls occasioned no gripes even from this
gripe-prone staff—the vibration will eventually tire even the sturdiest Belstaff-suited
Bonneville rider. And long before that will have occurred, the blurred mirror
will have irritated the rider enough to vary his pace. The convex Stadium
bar-end mirror fitted to the low bar is a vast improvement over the standard
flat Harley-style mirror, but even it couldn't clear up the fuzzies.
And that lack of effective rear-view vision could
be of some concern to the Bonneville rider, because the handling of the bike is
matched perfectly to the power of the engine—a certain recipe for full-throttle
back-road riding. Capable of 100 mph inside a half mile and of thrashing through
a quarter-mile in 13.41 seconds at 96.2 mph, the Triumph is clearly no slug.
Indeed, this year's MK-II carbureted bike, with no other performance changes
(including gearing) was .79 seconds and 3.5 mph faster than our '76 test bike.
No threat to the Honda
Six, to be sure, but respectable enough to keep
the men in the black-and-whites alert. After all, they're used to thinking of
Porsches as about the quickest things around.
None of this, of course, adds up to a bike that
could be thought "modern" in the same way a Suzuki GS1000 could. We expect our
motorcycles to be indestructible today, demanding even zero-maintenance from our
chains, and in those terms the Bonneville is a hopeless antique. It requires its
owner to understand everything about it, from the way the people at Meriden gave
its slick-shifting five-speed gearbox a left-hand shifter to the secret cure for
a leaking countershaft seal (ours didn't have the cure). It is a
high-maintenance machine, in both the mechanical and emotional senses. You
cannot buy a Bonneville simply to ride and park in your garage; you must, if you
are to expect any enjoyment from it, become its psychologist, doctor, riding
master and slave. Anything less will find you advertising it within the first
month of your purchase.
If this all seems a bit much to pay for a
motorcycle, consider this: Lack of techno-marvels and all, Triumph has slid
virtually unnoticed back into sixth place in American sales (behind Honda,
Yamaha, Suzuki, Kawasaki and Harley-Davidson), relegating BMW to seventh. This
is the first time since Triumph's glory days of 1973-74 (when 25,000 Trumpets a
year went out onto our streets) that such a thing has happened. That means that
more than 7000 riders will walk into Triumph showrooms this year, point at
blue-and-silver, black and-red or brown-and-gold Bonnevilles and ride out on
them, having been sold not by Fonzie, fads or flashy ads, but by the special
qualities of the bike: its simplicity, stability, styling and unexcelled
performance of the fundamental kinesthetics of motorcycling.
Rumors persist that next year's Bonneville will
see even more substantial changes than this year's: electronic ignition, radical
styling alterations and triple-disc brakes with Morris mag wheels. Whether or
not that will change the elemental character of the Bonneville remains to be
seen; after all, since its introduction in 1959 it has prevailed through a
history that would have killed most devices. But it has remained the beguiling
Bonnie, a ride unique in the two-wheeled world.
It's a ride that every motorcyclist should enjoy
at least once.
Source Cycle 1978

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