The Classic MotorCycle - February 2014

HOMING TIGER A Devon Triumph

STUNNING SLOPER Beautiful SG31 Ariel February 2014

Where legends come to life

Forgotten

treasure The oft-overlooked 500cc Matchless and AJS parallel twins

BROOKLANDS RECORD BREAKER Time-trialling Triumph

CULTURE CLASH

New Imperial rebuild, part one

Number 2,February 2014

RE-MINTING AN IMPERIAL

£4.10

Cotton Street Scrambler

INSIDE: BMW R50S restored: “I always wanted an ‘S’ version” Motocross, 1925 style – at the Southern Scott Scramble Model 50 Norton rebuild advice

When was the last time you saw a Wales-built Bown? Can’t remember? No, me neither. Welsh rare-bit indeed...

Event exposure

The Classic Motor Show attracts a very different audience to those who normally attend motorcycle-only events.

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Words and photography: JAMES ROBINSON

he Lancaster Insurance Classic Motor Show celebrated its 30th birthday in style as 65,000 motoring enthusiasts gathered at Birmingham’s NEC during the three-day classic event, over November 15-17 and though we featured it briefly on our news pages last month, there was actually enough of interest there to encourage a more detailed look.

From its humble beginnings of two halls (17,000sq m) and around 70 clubs in 1984, the 2013 Lancaster Insurance Classic Motor Show offered 11 halls (82,000sq m) with 269 motoring clubs creating amazing displays of rare and stunning marques.

With 1500 cars and 300 motorcycles on display and more than 600 trade stands, every motoring taste was catered for.

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THE CLASSIC MOTORCYCLE | FEBRUARY 2014

The Wall of Death had queues like this for much of the show’s duration.

Classic event | Motor Show

Daniel Nwaokolo, show director, said: “The feedback on our 30th show has been quite overwhelming and is a true reflection of the classic movement’s continued passion for the show. I’d like to thank everyone – all the clubs, exhibitors, visitors, special guests and sponsors for making it an incredible event and look forward to seeing you all again in 2014.”

Sporting Bears, the charity fundraising motoring club, raised around £41,000 over the three-days from offering 10 mile dream rides to visitors in cars ranging from an Austin Seven to the latest Lamborghini Aventador Roadster.

There were certainly some eye-catching motorcycles among the 300. Among them was a rare 1931 AJS S3, the ‘final hurrah’ from AJS of Wolverhampton before the Stevens’ family concern was taken over by the Colliers and Associated Motor Cycles was founded. The transverse V-twin was being loaned by the National Motorcycle Museum, and posed alongside a 500cc racing New Imperial, the supposedly ferocious handling V-twin created by New Imp ‘doubling up’ its successful 250cc racing single, from the same source.

AJS seemed to be well represented – another stunner was on the OC stand in the shape of the exHugh Viney ISDT machine (registration number AJS 5) 500cc twin, while an M7 Ajay was on one of the trade stands, too.

Standing out among the crowds was a Strongbowpainted Triumph twin (who remembers that late 70s attempt at importing US-style Dirt Track to the UK?) which was featured on a busy Triumph OC

“Among the eye-catching motorcycles was an ultra-rare AJS S3.”

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Triumph OC was among the many club stands which put on a good display.

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AJS only used ‘magenta’ for its tank panels for one season, 1929, which dates this ‘cammy’.

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The Strongbow Triumph. Nice.

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Rare AJS S3 came across the road from the National Motorcycle Museum.

stand, while equally packed Norton and BSA displays had some tasty kit, too, including a Manx-powered racing outfit, among a raft of cammies, on the former, with some well turned out sporting triples among the machines sparkling on the Beeza stand.

One of the most interesting aspects of the show is that it provides an opportunity for classic motorcycles to reach a new, different audience.

Sure, classic car owners will generally be aware of motorcycles, but here was a noticeably younger, family oriented audience at the NEC ‘do’ – so it can only be a good thing so many nice motorcycles were put in front of them, too.

The 2014 Lancaster Insurance Classic Motor Show will be held from November 14-16.

For more information visit www.necclassicmotorshow.com End

THE CLASSIC MOTORCYCLE | FEBRUARY 2014

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Underrated

contender

In its heyday, the 500cc AMC twin was among the most expensive money could buy.

Which makes them a comparative bargain now.

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rofiling the AJS Model 20/Matchless G9 498cc twins, I feel like a travel writer giving away the location of a wonderful little destination, and in so doing taking the risk of it being overrun.

These 500cc twins have been largely overlooked in favour of those from the Big Three (Triumph/BSA/Norton), and their reputation has suffered by loose association with their 600cc and 650cc siblings and their well-known crankshaft and vibration problems (another story).

Partly this is due to relative scarcity; in its best postwar year AMC’s Woolwich factory only produced just over 16,000 machines altogether, a third of Meriden’s bestyear output.

And the twins’ strengths were not sensational; they weren’t the fastest, or the best-handling. They were ‘just’ 500s. But they were built to an exacting standard, were comfortable and extremely satisfying to ride, and they were durable. Wally Wyatt, the AMC comp shop wizard responsible for boosting the Norton 750cc Atlas engine’s power to Commando levels, considered the 500cc roadster twin “a marvellous engine – I stripped a German rider’s bike with 83,000 miles up – it didn’t need a thing.”

Words: STEVE WILSON Photography: JOE DICK

But they were different, weren’t they?

Phil Walker’s engine design, when the twin was released for export only in 1949, was certainly that, featuring separate heads and barrels, and the famous third, middle main bearing, a split shell like a big end.

As the factory claimed, this allowed oil to be fed to a point centrally between the two big ends (unlike an end-fed crankshaft set-up), as well as ensuring perfect end location of the crankshaft. Later detractors believed that the middle bearing meant a lack of any whip in the crankshaft, and would contribute to unusually punishing vibration – but that was never a real problem for the 500s, except at extreme high revs.

Harry Larner, a quality inspector at AMC’s Plumstead factory, considered the middle bearing wonderful at stopping wear on the other two mains. Factory tests had showed that the centre bearing, while slowing the engine slightly, also kept the pistons pretty parallel in the bores, so that there was also appreciably less cylinder wear than on the BSA and Triumph opposition.

Harry detailed the care with which these engines were constructed. Flywheels were balanced, and with them a pair of con rods were made and marked together, being weighed to within 10g of each other (and subsequently polished). The same was done with a pair of the wire-wound pistons, with their finer clearances, which AMC made and used on the twins until 1954.

Super Profile | AMC 500cc Twin

These processes were not cheap and meant that the AMC 500cc parallel twins were almost the most expensive on the market. In 1955 they cost £240, when even BSA’s sporting A7SS 500 was £231, Ariel’s KH and Royal Enfield’s 500 £222, and the Speed Twin and Tiger 100 £210 and £228 respectively. Only Norton’s Featherbed-framed Dominator 88 topped them, at an unapproachable £259. And even with the premium price, AMC’s publicity man Ray Kennard later said that “the 500cc twins were said to have been produced at a loss since day one”!

However, in 1949 (or 1951 when they began to appear in the UK), they offered a lot for the money – swinging-arm rear suspension (there never was a

plunger AMC twin), alloy cylinder heads from the start, timing by gears not chains, and rider touches, from the easy-to-use eccentric rocker spindles for adjusting the valve clearances, to QD rear wheels, and AMC’s renowned fine finish, including distinctive, high quality chromed petrol tanks for the twins.

Initially claiming 26bhp and with a top speed in the mid-80s, this was a fine, versatile package, which returned between 60 and 70mpg. In the proven Heavyweight singles’ single downtube frame and cycle parts, weighing in at 394lb, the model was both comfortable, and robust enough for AMC’s US and Colonial markets. The ‘ripping calico’ exhaust note was a bonus.

Restoration guide | Expert advice

Norton Model 50 1959-on The specialist Many years ago, after Mike Pemberton’s L-plates were gone, he joined a family tradition of Norton ownership by acquiring his first Model 50. Skills in his home workshop increased in parallel with his career in the aircraft industry. In 2004, he turned his hobby into work when he set up Pushrod Performance, providing engineering facilities and knowledge that can overcome just about any Norton powertrain problem.

Pushrod Performance: 01257 471014

“The Model 50 became a favourite donor candidate for many Tritons.”

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Model history

Norton introduced the 350cc Model 50 in 1933 as a stablemate to the well-established 500cc Model 18 and ES2 models until hostilities called a halt. Postwar, the 500s soon resumed production. The Model 18 finished in 1953, but in 1956 the Model 50 finally reappeared to join the ES2. The single down-tube, swinging-arm frame, common to both models, was perfectly adequate to corral approximately a score of horses generated by the standard 350cc motor.

Presumably it was a production economy that decided, from 1959-on, the Model 50 and the ES2 were to be endowed with Featherbed frames and cycle parts. This rather over-egged the pudding.

In 1961, in common with the rest of the Norton range, the bikes went over to the ‘slimline’ version of the Featherbed. While the bike was a steady seller, the Model 50 became a favourite candidate for eviction of the standard engine to be replaced with a Triumph twin to create another Triton. By the early 1960s, Norton saw its twin cylinder models as the way forward and both Model 50 and ES2 vanished after the 1963 model year. Hence, unmolested overhead valve Norton singles are uncommon, have their own character and are far more affordable than the overhead camshaft models.

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Words: ALAN TURNER

Engine

Most Norton engine designs were exceedingly long-lived and the Model 50 was no exception. e 71mm bore and 88mm stroke dimensions were established in the 1920s for the company’s 350cc models. ey remained unchanged for the 30 years that spanned Model 50 production. Construction of the overhead valve engine was straightforward, with the valves driven by two separate cams giving the

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distinctive appearance of the engine’s timing side. e later engines had an alternator and coil ignition superseding the magdyno of earlier models. Poor performance can often be traced to valve seat recession. is is not easily sorted as the factory production methods cast the heads around the guides.

However, Mike Pemberton can machine the head for new seats and make up suitable valve guides in Colsibro. Apart from castings, almost

The ClassiC MoTorCyCle | FEBRUARY 2014

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everything is still readily available for the Model 50. e original cast-iron flywheels are interchangeable, subject to an oilway being drilled, although Mike also offers upgrades in steel. Major NLA components are the con rod (rarely a problem) but the oil pump can be more troublesome. A barn-find engine may well have a seized oil pump.

Trying to turn over the engine could cause terminal oil pump damage. At present, noone makes replacements!

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Gearbox

e transmission is perfectly adequate for far greater power outputs, so is hardly stressed by a standard Model 50. If the primary chain needs replacing, make sure proper motorcycle chain is used. Cheaper, industrial quality chain is not suitable. An alternative is to uprate to a belt primary drive. Mike has been using such a conversion for some years and the belt remains in fully serviceable condition. e

clutch is the same as that fitted to Norton’s twins, but the Model 50 uses two less plates. All clutch parts are available, up to and including a complete assembly. Since inception, the Model 50 was always fitted with a four-speed gearbox and bikes from 1956-on used the wellproven ‘lay-down’ AMC-Norton unit, for which everything is available. Problems mainly stem from inadequate lubrication.

Mike recommends the use of 80/90 gear oil.

Classic life Pricing

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Model 50s may not be rare, but they are not plentiful either, so the price ticket on a top quality Model 50 with everything in first class order might read £6000 or upward, basic running machines possibly a thousand or so less.

However, basket cases are becoming extremely rare, reflected in £2500 being asked – and paid.

Final bit

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Electrics

Cycle parts

Suspension

e first postwar Model 50s were fitted with Lucas Magdynos. e Featherbed model adopted Lucas alternator electrics, with battery and coil ignition. e six-volt system is good, but can be easily uprated to 12-volts with the aid of modern black box electronics and the appropriate bulbs.

Replacement wiring harnesses are available, but are fairly straightforward to make for completist restorers.

Tinware for the Model 50 can be very tricky. e two-part pressing that gives total enclosure of the rear-chain approaches the ‘mule feathers’ rarity zone.

Pattern mudguards are available, but at a price. e Norton Owners’ Club is probably the best source of information for finding someone who can help.

For tyres, Mike notes that K81s are effective with the earlier frame, but Avon Roadriders work well with Featherbed models.

Front suspension is courtesy of Norton’s short Roadholder forks. e long Roadholders were fitted to pre-Featherbed Model 50s. Knowledge is easily found, as are parts, even the sliders.

An over-tightened spindle pinch bolt can result in a cracked slider. Depending on the extent of the damage it may not be possible to effect a repair.

e swinging arm moves on Metalastik bushes. ese rarely need replacement, but if they do – a hydraulic press is very useful. e twin coilover units of the rear suspension can be selected according to budget and riding style. Basic units can be used for ‘steady progress’ riding, more enthusiastic users might appreciate the quality of the ride offered by units such as those from Hagon.

Faced with a choice, the Model 50 may seem a slightly quirky alternative to the ES2, but Mike Pemberton explains that the two motors are different in character. The long stroke ES2 is the plodding version, the ‘50’ needs to be revved to make progress, although it is all relative. Shed finds still turn up with the ‘coffee shop racer’ look thanks to the huge aftermarket parts availability for Featherbed frames in the 1960s. Mike’s ‘Poor Man’s Manx’ project is an example of the modern approach. A single he built from parts, the bike now serves as a test bed for the modifications and upgrades offered by Pushrod Performance. As well as straight repair and restoration work, Mike can also provide upgrades to an engine as required.

It may well have exasperated Norton’s sales department that customers still preferred its anachronistic Model 50 to 1960s upstart Navigator, but longestablished, soundly-engineered motorcycles were what buyers expected from Bracebridge Street. Now, as then, a Model 50 has practical vintage charm in a modern package.

The ClassiC MoTorCyCle | FEBRUARY 2014

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