5 OccBSADBD34 Gold Star and 500cc Velocette Venom Thruxton Mick Duckworth

OME British have be- When the factory produced a hot new Venom. They were entered by dealer teams come more like holy icons than motor 500cc sportster with an all-alloy engine in in the annuallong-distance race for show- vehicles. They are cherished, polished 1937, a BMRC Gold Star award for a room models at the Thruxton eircuit. S and revered. But not used much. 100mph lap at Brooklands made a fitting Goldie exponent Eddie Dow fielded Vipcrs BSA's Gold Star and the Velocette launch. And provided a model name that in the event, but the most influential Velo Verrom Thruxton are typical of machines could be used on a line ofhigh-performance protagonists were Reg Orpin and Geoff that get put in this category. As the arche- singles up to the early sixties. Dodkin. typal 500cc sporting singles of the fifties The Gold Star gave BSA a tremendous American tuners had been busy, too, and sixties, they have star status in the run of sporting success in postwar years. tweaking off-road Velocette singles expor- classic galaxy. They are also relatively Even in road racing, an activity Small ted since the forties. The fastest stateside rare, which makes them very expensive. Heath shied away from after disasters in machine was that entered in track events And they are fickle beasts, demanding the 1920s, it proved a winner. It was sold in by Los Angeles dealer Lou Braneh. Its sympathetic handling. 350cc B32 and 500cc B34 versions, which secret was a special cylinder head with a Consequently, many examples probably evolved in to the definitive, most sought- massive 2in-diameterinlet valve. wouldn't get as far as the nearest corner after Goldie, the 500cc DBD34 firsf made Clubman versions of the Viper and shop without causing trouble and exas- in 1956. Venom became available in the fifties, but peration. They don't do the mileage a The 85 x 88mm B34 pushrod engine had eventually US experience, and Orpin's machine needs to stay in good fettle. been tuned alm ost to the pitch of an over- enthusiasm for a cireuit-racing Velocette, This can make life difficult for press head camshaft racer. A lot of credit for the had its effect on the factory, resulting. in testers. Even when running ex am ples are 500's output of 40bhp at 7000rpm goes to low-volume production of the Venom found, they may be eosmetically excellent Roland Pike, developmentengineer at BSA Thruxton. Based on Orpin's 1964 500ee but disastrously unreliable. Or, justifi- from 1952 to 1957. And unlike his counter- Thruxton winner with a big-valve head, it ably, an owner may not want someone else parts working on AJS, Matchless and was on sale from mid-1965. riding their pride and joy, Which is why Classic Bike was lucky to find these two examples of single minded- Equipment ness. The Gold Star, a 1958 DBD34 model, belongs to John Simmons of Ipswich. A Both singles only As limited-production machines aimed al long-time BSA enthusiast and member of committed sporting riders, both singles the BSA Gold Star Owners Club, John only ever claimed to provide speed anti. acquired his Goldie three years aga and euer claimed to roadholding. Owners ean treat any other lost no time in restoring it to a superb state attributes they discover as bonus points. of originality. He enjoys group riding, prooide speed In each case, apre-war engine design even though his nearest clubmates live 50 has been the subject of gradual develop miles away. On a fine weekend he typic- and roadholding ment. Although its manufacture ceased ally covers 250 miles. before the Thruxton's appearance, the Neal Barry, a member of the Velocette Gold Star unit is more modern in its all- Owners Club from Bracknell, provided the alloy eonstruction and its higher-revving' Thruxton, a 1965 model. He has owned it Norton projects, he worked under the con- capability. for twelve years, and keeps it in slightly straint of having to make the Gold Star Both engines have a built-up crankshaf non-standard trim with a British Racing acceptable for ACU Clubmans racing, and roller-bearing big-end. The Velo's Green eolour scheme and single seat. But, which demanded an almost road-Iegal crank and its casing are narrow enough tl1 having raced Velos in the past for special- specification. put the primary drivechain inboard of'the ist tuner Geoff Dodkin, he has, appropri- The Gold Star was made during prosper- final transmission line. The crank in thE ately, made his maehine into a replica of ous years at BSA. But Velocette's Venom test Goldie was found to have a crack one ofthe singles entered in raees success- was one of the final products to come from across most of one flywheel when restored fully by the southwest London dealer in the Hall Green factory before closure in probably due to non-standard lightenin the sixties. He regularly rides it on the 1971. The 86 x 86mm 499ce single was the work carried out in the past. It now runs road as weil as parading the Thruxton at ultimate development ofthe M-series push- with a newly-made component from Brit CRMC race meetings. As it came from the rod engine designed by Charles Udall and ain's Gold Star Service. factory, the Thruxton was finished in either first used in the 1933 250cc MOV model. Design contrasts in the valve gear affec blue and silver, or black. Although the company built a sporting maintenance procedures. The Thruxton reputation on the strength of its pre-war has hairpin valve springs and no tappet ohc K-series machines, it opted to focus on gap between its pivoted cam followers ane History the utility market in the postwar period. rockers. This means removing the timing But when the lightweight 200cc LE water- cover to adjust clearances. On the Gole The giant Birmingham Small Arms com- cooled flat twin flopped, the pushrod Star, gaps are set by rotating the rocket pany spotted a major trend in the motor- single was revived. spindIes in eccentric housings. The BSA cyele market in the mid-thirties. The sports Possibly influenced by BSA's success has two separate camshafts, while tht and recreation machine was supplanting with the Gold Star, Velocette introduced Velocette has two lobes on one shaft. Bot] the go-to-work utility bike that BSA had sports versions of their road 350 and 500ec use trains of gears to drive cams, mag specialised in. singles in the mid-fifties: the Viper and netos, oil pumps and rev-counters.

26 Classic BikE

ROADTEST .ve maintenance is often a feature This involves slipping the elutch, which set up it can cause trouble, but the test : en . es meant mainly for competition, is liable to respond by overheating and machine's worked nicely, though opera- - -' eowners ofthesemachines both say refusing to free. Its draggirig prornotes tion was a little heavier t.han on the BSA. a they find little tinkering is necessary stalling and the owner's ride becomes a A notable feature of the Velo gearbox is a oncethey had mastered basic adjustments. misery - especially if kick starting is un- kickstarter mechanism that only prornotes Crirical amongst these is carburation, but reliable, as it often is. minimal rotation of the with the Amal GP racing type fitted in each To John Simmons' credit, this Gold Star each swing. ca e does ha ve the virtue of simplicity . No was particularly well-behaved. He can In keeping with the Thruxton's gener- time need be wasted on tick-over settings, start it readily - a novice needs a little ally outmoded specification it was built for which the GP has no provision. practice - and despite the RRT2 box and a with a pressed-steel primary drive enclo- Both singles have distinctive exhaust sure: the Gold Star acquired an alloy systems. The Velocette's fishtail had a casing in 1952. camp, archaie look by the sixties, but it Gold Star The Velocette's frameis elearly an adap- had to be fairly efficient to permit speeds tion of an earlier rigid type. Its excellent of 129mph - a figure recorded by the FOR: instant power, glamorous handling has always been a source of Thruxton-based machine which won the style, slickgearchange wonderment to those who notice how little 1967500ccProduction TT. AGAINST: awkward bottom visible support there is for the swinging Its swept-back front pipe mimics the arm pivot, Hanger plates for the Thruxton Gold Star: as tyres improved the normal gear, brakes only adequate, rearset footrests may appear to add style of header pipe robbed machines of anti-social noise bracing, butin reality this is unlikely. cornering elearance. The BSA's stocky An all-welded duplex frame was one of PMn pipe terminates in one of the best Thruxton several major contributions made to Gold known components ever made for a motor- Star development by Bill Nicholson, cyele, the Gold Star sileneer. In fact, silen- FOR: responsive handling, BSA's star off-road rider of the postwar cer is not an accurate term, as BSA never effectioe brakes, flexibility period. Like Norton's Featherbed it fixes elaimed it to be road legal. A megaphone AGAINST: cramped the extreme ends ofthe swinging arm pivot made to look like a road muffler, it boosted firmly in gusset plates. the machine's power while satisfying the accommodation, tricky The Velocette can elaim to have more rules ofClubmans and production racing. gearchange, poor kickstarter advanced front suspension than the BSA. Exhaust sound is one of the most strik- Its telescopic fork is a two-way damped ing differences when you go from riding type developed for the fifties' scrambler. For one machine to the other. The BSA's note standard six-spring elutch which some the same level of sophistication, Gold Star is harsher, especially as the throttle is owners junk in favour of a BSA/Triumph owners have to seek the Superleggera fork opened and revs elimb. or Norton four-spring type, there were no conversion once marketed by Eddie Dow. Noise is an increasing liability among transmission hassles. The elutch action The Velo fork also incorporates substan- today's well-silenced vehieles. And with was commendably light as well. tial bracing via the mudguard stays. A the RRT2 gearbox ratios fitted to most The Thruxton has a close-ratio gearbox, Clubmans DBD34s, there's a lot of it. The but without an ultra-high bottom ratio. infamous high-ratio first gear suitable for The elutch is a heavy-duty version ofVelo- Below: Amal GP carburettor and large- racing means using high rpm to move off cette's extraordinary design using a diameter exhaust are part of Clubmans from astandstill. hinged thrust-cup and tiny springs. Badly Gold Star track tuning e rear, the Velo also boasts movable ish machines before the alternator era. the rev-counter's red area starts at " ring/damper units for adjustment of John Simmons has fitted a brand new 6200 and a softening-off of power was feIt springrate and wheel suspension travel. instrument bought at the Stafford CB in this rev region at times, suggesting A twin-Ieading-shoe front brake is a defi- Show. A Lucas KIFC competition mag- valvefloat. ite plus for the Thruxton, which pulls up neto provides ignition on the Thruxton, Roadholding is first class in both cases, uch more sharply than the BSA with its though later versions were equipped with but the Velocette feels nimbler and more single-leading-shoe drum of the same dia- coil ignition. Some final models had alter- ready for quick changes of direction. On meter (190mmor 71Mn). nator electrics. minorroads, however, theThruxton's sus- As the first machine other than an out- Devoid of a centre stand, the Velocette pension feit hard to the point of discom- and-out racer to be sold by a British fac- has astout, easy-to-use prop stand. Gold fort, making it all the more difficult not to rory with clip-on handle bars and rear-set clout the fairing with parts of your body. footrests, the Gold Star probably started This effect may have been aggravated by the cafe racer trend of the sixties. The What are they worth? an unyielding seat, riding posture that results will not suit all Although not as reassuring as the riders: it's not a position that makes much BSA DBD34Goid Star Velo's, the Gold Star's front brake proved sense under 60mph. .E6000-.E10,OOO adequate if its lever was squeezed hard The Velocette is similarly tailored for enough. When it is used in earnest, the peed work. Its 'bars feit more compact Velocette Venom Thruxton plunging reaction in the forks is more and the original-style AR9 racing fairing .E6000-.E12,OOO marked than on the Thruxton. On both fitted to the test machine will cramp the machines the rear brakes are useful for style of anyone over 5ft lüin. I preferred slowing and giving a right-turn signal the Velo layout, however, feeling rather Star centre stands tend to wear badly at simultaneously without them grabbing or high-perched on the Gold Star in compari- the pivot points, probably because owners wheel-Iocking. on. kickstart with the machine on the stand to Except for one occasion when it needed a When you get your knees and elbows getmore weight behind thejob. push to fire up, the Gold Star started easily tucked in on the Thruxton, the twin if the timing lever and exhaust lifter were Smiths instruments point uselessly at used carefully. John swears by Lodge your ehest, The less steeply-angled clocks Perlormance 2HLN plugs, putting his trust in no other on the Gold Star can be readily checked at type. speed, although being ofthe Chronometrie Neither of these machines will give plea- Neal, who fits a KLG FEIOOin the Velo- design their needles don't swing as sure to the laid-back lane cruiser. 'You've cette, suggested a starting drill which smoothly as the magnetic type on the .really got to ride it,' is how J ohn sums up proved infallible. Find compression, lift Velo. The oldcr instruments often prove his Goldie. Hold lower gears and stoke up the exhaust valve and swing the kick- longer lasting, though, the revs and on a clear road the Gold Star starter right down: let it return to the top of Six volt lighting makes the singles legal . shakes offits low-speed awkwardness and its swing, then kick. Life may have been in poor weather and darkness. What light flies. Youcan hang on in second gear up to made easier by the compression plate the Velocette's headlamp can produce 90mph. under this machine's barrel, which eases with current from a belt-driven Miller The Velocette puts on speed more quietly compression down from 9.2to 8.5:1. dynamo tends to be dissipated by the fair- and less dramatically. But give it time, Changing gear on the Thruxton is made ing's perspex.nose-cose. The BSA uses the and it whistles along deceptively quickly. tricky by the pedal's inaccessibility. Down- Lucas Magdyno widely specified on Brit- Neal Barry suggested revving to 6000rpm: ward changes were particularly awkward

Above:the Above: original caie Thruxton's racer contral carburettor layout feeds cylinder via 2ininlet valve

Left: Velo's instruments Left: tls arehardto frantbrake readonthe is Velo plus move point

:J 1990 29 ROADTEST as you must slot the toe ofyour boot control of a Gold Star it pays to slip into between the exhaust pipe and the pedal neutral as you pull to a halt. On this Conclusion before it can be snicked up. The remote machine it was perfectly easy to do. This test proved that the ultimate British linkage used with rearset footrests adds The Velo seemed more mechanically sports single can be reasonably manage- uncertainty to the operation. noisy, though this was probably an acous- able when properly prepared and regu- The BSA RRT2 box may not be sup- tic effect produced by the fairing. Its larly exercised. But it is most definitely a remely practical for road use, but its opera- engine not only looks more old-fashioned mount for the free-flowing highway and tion is superb. Using needle roller bearings and bitty than the Gold Star's, it also not clogged-up town roads. where most makers had plain bushes, it sounds more like a vintage machine. When In terms of style and historie import an ce gives a slicker change than the much- idling it makes a sort of 'rockle-tockle' the Goldie wins hands down. It was very praised AMC Norton box. To maintain full noise worthy of a Banbury Run entry. much a machine of its time, setting stan-

30 ClassicBi dards in performance as weil as appear- the Velo's fairing off, its mechanical parts ance. The Thruxton was obsoletewhen it are too untidy to rival the chrome and was launched: in 1965 it had to contend alloy curvature ofthe BSA unit. specifiattiuns with Suzuki' s250cc T20 six-speeder. On the road, the Gold Star has the edge Judging between the machines on looks in delivering raw power and surging is a matter of personal taste. The Velocette acceleration. It has a ferocious, revvy BsADBD34 VELOCETTE combines a sixties' sleekness with a touch engine that the Thruxton unit didn't of coach-lined antiquity. But can it com- surpass in the sixties. But what the Velo- CLUBMANs VENOM pare with the bare-metal elegance of the cette does offer is a lower-slung, more GOLD STAR THRUXTON Gold Star, surely one ofthe most exciting- manageable package with better braking looking motorcyles ever made? If you take and a surer front end 0 ENGINE

Type: ohv single Type: ohv single and : Bore and stroke: 85x88mm 86x86mm Capa city: 499cc Capa city: 499cc : Compression ratio: 9:1 8.5:1 (9.2:1 standard) Carburation: Carburation: 1Ij,inAmalGP 1%inAmalGP Output (claimed): Output (claimed): 40bhp at 7000rpm 41bhp at 6200 Electrical: Lucas tlectrical: Lucas Magdyno, 6v battery K1FC magneto, Millerdynamo,6v battery TRANSMISSION

Primary drive: Primary drive: single-row chain single-row chain Clutch: multiplate, Clutch: multiplate, wet wet Gearbox: 4-speed, Gearbox: 4-speed, elose ratio elose ratio CYCLE PARTS

Frame: tubular, [ull Frame: tubular, full cradle, twin cradle, single downtubes downtube Suspension (front): Suspension (front): telescopic fork telescopic fork (rear): swinging (rear): swinging arm, twin Girling arm, twinHagon units units (Girlings standard) Tyres (front): Tyres (front): 3.00x 19in Avon 3.60 x 19in Avon Speedmaster MkII Roadrunner (rear): 3.50 x 19in (rear): 4.10 x 19in AuonGP Avon Roadrunner Brakes (front): 7.5in Brakes (front): 7.5in (190mm) sls drum (190mm) tls drum (rear): 7in (178mm) (rear): 7in(178mm) slsdrum slsdrum Wheelbase: Wheelbase: 56in (1422mm) 54. 75in (1391mm) Seat height: Seatheight: 30.5in (775mm) 30.5in (775mm) Ground clearance: Ground clearance: 6.25in (159mm) 6.5in (159mm) Kerb weight: 4101b Kerb weight: 4151b (186kg) (est) (188kg) (est) Fuel capacity: Fuel capacity: 4gal (18.2litre) 4.25gal (19.3litre)

PERFORMANCE

Top speed: Top speed: 1l0mph(est) 110mph (est) Fuel consumption: Fuel consumption: 45-55mpg 45-55mpg

Left: the singles lose their low-speed awkwardness on open roads

July1990 31