Good and Bad Vibrations...casual reflections on two classic vertical
twins
There were two vertical twins on the
mid-week run this month (February).
One was Ed Sleightholm’s 1971 BSA 650. The
other was my 1973 Laverda 750.
Reflecting on a great day’s riding on the
sinuous roads that wind through the valleys and over the ridges of the
Dandenong’s, I found myself comparing the stories of these contemporary
machines.
Seeing Ed’s nicely restored BSA had
reminded me of the first time I had a close look at one. It was in 1972, when I
was riding my BMW 50/5 from London across Asia. One afternoon, in January, in a
steamy hamam in Istanbul, I met an Irishman (“Mike”) who had ridden his BSA
from England. It was mid–winter. We discovered that we were both, having been
told by the locals that the roads were closed and that it was therefore an
impossible journey, pondering the challenge of getting our bikes across Turkey
to Iran so that we could continue on as planned through Afghanistan, Pakistan
and India.The route to Iran passed
through remote, snow covered, mountainous country, past Lake Van and Mount
Ararat, where Noah’s Ark was said to have come to rest.
As it turned out, Mike and I discovered
that we could put the bikes on a train to the Iranian border. That trip proved
eventful for me when my BM was “mislaid” by the Turkish (or, possibly, the
Iranian) railway en route, and not recovered until after two or three
nail-biting days in a remote village railhead in western Iran. Mike and I later
rode independently to Nepal, meeting up from time to time.
I mention this only to enable me to record
that whilst my BM purred smoothly along, without complaint or problem, Mike’s
BSA marked its vibrating progress across Asia by depositing a trail of
components which had given up the struggle against metal fatigue, as well as a
stream of luggage which became divorced from his perpetually fracturing luggage
rack. Mike became an expert in locating village welders, and patiently waiting
for work to be done in unconventional circumstances and ways by men and boys to
whom the clock was a foreign device of the devil. The BSA became rougher and
rougher in looks and performance. The last I saw of it was shortly after his
(marginal) brakes had failed to enable Mike to avoid a collision with a road
gang in the Nepali foothills, and Mike was forced to flee as fast as the
battered drab green Beesa would carry him, to avoid being lynched.
Ed’s
burgundy beauty, fed through two Amals, is certainly better looking, and
slightly more exotic in spec, than Mike’s was. My instinct is to prefer the
simplicity of Mike’s single carb, especially for touring, and notwithstanding
that his engine might be smoother because of them, Ed used some colourful
expressions when describing to me the getting and maintaining of Amal
synchronicity on his beast.
My knowledge about the history of, and
design differences between, Triumphs and BSA twins is scant, but I understand
“from my books” that the 1969 and 1970 650 Bonneville’s are regarded by many as
the best Brit vertical twin of them all, partly because of a new crankshaft,
with a heavier flywheel, introduced in 1969. BSA, I gather, ceased making twins
in 1972. Moreover, I gather that the consensus also is that the change by
Triumph, in 1973, to 750cc was seen as a market necessity to counter the Honda
four, but that it was in fact a disastrous change which resulted in increased
vibration and other weaknesses. Rubber mounting the Norton Commando engine
helped to disguise the vibration problem for a while, but was a precarious,
unsatisfactory, response.
Co-incidentally, on our run in the
Dandenong’s, while Ed led the way on his BSA, Bill Weedon followed serenely as
“tail-end Charlie” on his ex-police Honda Four!Subject to what follows regarding my Laverda, it could have been an
evolutionary time line in motion on the road!
While the British were floundering with
their vertical twins, and were piling eggs in the Trident basket, the Laverda
brothers in Breganze were developing their very successful 750 vertical twin.
First marketed as a 650 in 1968, by 1971 (when Ed’s 650 was the hope of BSA)
the chunky Laverda’s, grown to 750cc, dominated European endurance racing and
were, albeit expensive, in demand as road bikes in touring and sporting forms.
By 1974 (while the Brits, ignoring engine design and quality issues, applied
rubber blocks to vibration in their Commandos, and the year before the final
collapse of Meriden), the experienced and respected Dave Minton, in a
wonderfully atmospheric piece in “Motor Cyclist Illustrated”, described his
test of a Laverda750 SF in an article he entitled “Simply the Best Vertical
Twin Made”. As Minton put it, “so much has changed between (the traditional
British Twin) and now, it is hard to believe that the Laverda 750 SF has its
origins in the machines of yesteryear”. After a day on his test Laverda, Minton
summed it up as “one of the most exclusive and exciting motorcycles on sale
today”. What a contrast to the flagging status of the British twin at that
time!
Why did the vertical twin flourish as a
Laverda, and fail in England? In what ways was the Laverda vertical twin
different, and so superior?I don’t
intend to prolong this note to answer those questions. Those interested will
make an effort to investigate. Perhaps appetites will be whetted by the
following (not, perhaps, entirely satisfactory) quotes, also from Dave Minton,
from “Motorcycle Sport”, July 1973. Minton first asserted that the Laverda was
“really too good for this country. It is, supremely, a high speed tourer, able
to cruise for hundreds of miles at very high speed, looking as cool, calm and
collected at the end as at the start”; On the question of the configuration of
its “gutsy” engine. Minton said:
“One is still forced to the
conclusion that, when the chips are down, it has this
built in problem. It is still
a vertical twin! Naturally this has virtues as well but
it has one big almost
insurmountable vice: a vertical twin by its very definition
vibrates and even Laverda,
with what must rate as one of the most robust,
carefully designed and
assembled engines made, have been unable completely to
cure the problem.
It is a strange kind of
vibration that one experiences on the Laverda. Certainly it
is not difficult or tiring to
live with and, if one is trying to categorize the situation
“low frequency” would be the
nearest one could get—but it is not that really. It is
just that one is aware, all
the time, of the power of the motor. It comes up to the
rider in heavy throbs. Not
unpleasant ones, it is just there. Perhaps that is why
some people who ride Laverdas
are so enthusiastic? They like the feeling of
power this machine transmits.
We can understand it”.
The brilliant Laverda 750 vertical twin
evolved, and was generally available until 1977 (some two years after the last
850 Commando), when the factory decided to concentrate on its more powerful
(and lighter!) 1000 triple. Triples were made at Breganze until 1989 (some 14
years after the last Trident!).
Such were my thoughts as I relaxed at home
after our day in the hills this week, grateful once again for Ed’s enthusiasm
and generosity in organising these runs, glad that he had ridden his very nice
BSA, and very happy with the pleasures of my own superb vertical twin.
