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Ride it
like a Honda
Quick spin: 1949 Sunbeam S7 Deluxe
(Guy 'Guido' Allen, Dec 2024)
Post WWII optimism meets some
modern re-engineering. That seems to work
Young Phillip White was on the blower.
Apparently I had to ride his Sunbeam S7 Deluxe. This,
in case you didn’t know was a development of a lovely
and now rare exercise in post-war happiness, backed by
the then giant BSA.
The history of Sunbeam S7 to S8 series is troubled and
highly entertaining. While the Sunbeam brand was once
famous for high-end and quick single-cylinder
motorcycles, in 1943 it was, through economic
necessity, taken over by the larger and more cashed-up
BSA.
And it’s the post-war optimism that defines the S7 to
S8 series. Keep in mind that in 1946-47, the idea of a
tandem 499cc twin, with aluminium cases, overhead cam,
dry single-plate clutch and shaft final drive was
radical.
At a price of GB£222, it was hugely expensive and one
of the three most costly production motorcycles then
available in the UK. While a brave design it needed
more development. The worm drive in the rear shaft was
a weak point, necessitating a downgrade in the engine
tuning. Vibration was a massive issue in the early
offerings. To the point where a batch sent to South
Africa for police duties was famously sent back.
We owned an S7 for a couple of decades and ended up
getting it re-engineered by young Mr White and fellow
classic expert Doug Fraser. It was a long and
fascinating journey, some of which
you can see here.
Knowing I’d had a troubled history for the series,
White decided to change my view. He’d built an S7
Deluxe which, at least in classic bike terms, was
reliable and more or less idiot-proof. Interesting
idea.
Before accepting that premise, let’s talk through his
thoughts on the series. “BSA gave Erling Poppe (the
original designer of the S7) 10 minutes to clear out
his desk and get lost,” says White. “Then BSA
engineers took over because the project was heading
for the rocks. It was supposed to be their flagship
program – this was the future of BSA.
“They did a number of things to his
design. They altered the angle of the engine by three
degrees and had figured how to rubber-mount the things
after the South African experiment.
(Ed's note: a fleet was famously sent
out to South Africa in 1947, for escort duties for
Queen Elizabeth II's tour of the country and then
on-going police duties. They were famously sent back
post-tour for having unacceptable vibration.)
“They got rid of the rag-damped forks, which look like telescopic forks but all they have inside is oil-soaked rag and a centre spring box.
“Back when the pre-production models were built, they had a crossflow head. They could do 90mph – this is 1947 – but they lost a couple of test pilots because they couldn’t keep them on the road.
“The whole story of the Sunbeam S7 was
for a while one of steadily being detuned rather than
fixed.
“When it came to the rear drive, the
designer wanted a crown wheel and pinion. BSA owned
Lanchester cars and the drive on a Sunbeam is the
steering box out of a Lanchester.
“It’s not ideal. However let us not
forget that a Sunbeam S7 with sidecar won a gold medal
in the ISDT – that’s pretty tough going. There is a
rumour they stuck a new rear drive in every night!
“It’s a bronze worm drive and the tragedy with that is
when the hypoid oils came in, BSA printed advice that
you must not use it, however the printer left out the
word ‘not’. That established the bad reputation of the
drives, as they were destroyed in a few hundred miles.
“Remember at the time this was built, BSA was still
making cast-iron side-valve singles. For the average
mechanic at the time, the idea of an overhead cam with
self-adjusting chain tensioner, in an aluminium casing
was like something out of Mars. Just unbelievable.”
So, a disaster, yes? No. The very
early S7 Phillip and Doug revived for muggins
(above) has turned out to be an easy-going gem. Though
we will admit it’s used sparingly.
What really sent us down this path was Phillip’s S7
Deluxe, which he comprehensively rebuilt and then
offered for a test run. And here’s the bit that got my
attention: “Ride it like you stole it,” he said, “Or,
if you prefer, like a Honda. Don’t be afraid to rev
it.” Really?
This is exactly the opposite to what you’d say to a
new rider on my first-gen S7, no matter how
well-sorted. So what’s different?
“It’s been an evolutionary thing because when I first
got my bike back together it was the most unreliable
bike in the world because the distributor is hard to
access. What had happened – which I hadn’t seen before
– was the contacts had delaminated inside the spring
and there was a short between the bearing and the
contact. If the bike was cool it was fine, but when it
was warm it wasn’t, so you couldn’t find it.
“I converted it to electronic ignition, which I
normally don’t do, and it was just easy. I’ve also put
an alternator inside the generator casing up front,
which has essentially given me modern electrics. That
was the biggest upgrade.
“They’re prone to oil leaks. If you read the Sunbeam
Bedside Companion book (got to love that name),
they talk about various ways to stop leaks, but in the
end they say carry a rag with you and get to the
meeting site first!
“Stewarts were given an experimental
filler cap cum breather but they wouldn’t sell it. But
they gave it to me and that was the end of the oil
leaks. It’s now like a Honda.
"It will weep if you’re weeks and weeks on the road,
but if I just go out for a ride and come back, there
are no leaks. The unit is a tower with a dipstick,
with another tower over the top and they can breathe
through that.
“That was one of the single biggest things. Their
breather system is quite baroque.
“It will do the freeway and you’ll notice how around
Melbourne that our speed limits have dropped – so
Sunbeam owners get the last laugh.
“The world is changing to suit the Sunbeam!”
Okay, I’ll bite…what’s it like? I’ve ridden a few of
Phillip’s motorcycles over time, including a lovely 1937 Royal
Enfield KX V-twin (above) which I still regret
not buying, and his advice has generally been spot-on.
If you’re a little familiar with older (say pre-1960)
motorcycles, the S7 Deluxe represents no great
challenge. In this case the front brake had been
upgraded – by far the biggest issue with machinery
this age. And it did exactly what the owner said.
It started easily, galloped up the freeway to our photo spot, and then back again with no fuss. It would hold 100km/h perfectly well, though I got the sense 90-ish would be its happy place. Pretty good for a 70-year-old 500cc motorcycle.
The suspension was rudimentary but
good for the period, while the upgraded twin-leader
front drum brake worked. Albeit a little gradually by
current standards, but well enough to stave off
problems in current traffic and far better than stock.
And here's the real attraction: the
S7s with the balloon tyres are a stylish motorcycle.
So was he about to sell it? “Not that one,” said
Phillip. “They’re a much laughed-at model in old bike
land, mostly by people who have never ridden one.
Which is why I like to expose people to it. If you
don’t they end up in museums. If someone can say they
rode a Sunbeam and it was nice, that’s striking a blow
for the future of our hobby.
“They are beautiful – a late art deco masterpiece,” he
concludes. Amen to that.
Okay, so what's with the picture of the Queen? That's installed in what used to be the tax disc holder, cast into the left headlight bracket of the series.
Know your Sunbeam S7-S8
There are three key models of the series:
S7 from 1946 – only in black and with reverse
handlevers. Stewart Engineering in the UK – which is
the world’s only parts supplier – estimated some time
ago that there were less than 200 left, of which maybe
half were running;
S7 Deluxe from 1949 – re-engineered by BSA, painted in Mist Green or black, with normal handlevers;
S8 from 1950 – the same mechanicals as the Deluxe, but
now running slim UK motorcycle wheels and tyres
instead of the balloon rubber more usually associated
with Harley-Davidson and Indian of the period.
Generally in silver grey or black (there were
variants), with a very different muffler.
The S7 Deluxe and S8 were for a time
sold side-by-side.
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