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Velocette Venom Thruxton

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Make Model

Velocette Venom Thruxton

Year

1965 - 70

Engine

Four stroke, single cylinder, OHV

Capacity

499 cc / 30.5 cub in

Bore x Stroke

86 x 86 mm

Compression Ratio 9.0:1
Cooling System Air cooled
Lubrication Dry sump
Carburetor Amal 5GP2 carburetor
Exhaust Single, megaphone
Spark Plug KLG FE220 / NGK B9ES

Ignition 

Miller D6 with auto volt regulation
Battery 6V, 60W
Starting Kick start

Max Power

31 kW / 41 hp @ 6200 rpm

Clutch

Dry, three-plate

Transmission 

4 Speed constant mesh, close ratio

Gear Ratios 1st 8.4 / 2nd 6.3 / 3rd 4.83 / 4th 4.4:1 (TT close ratio optional)
Final Drive Chain

Frame

Single down-tube and twin bottom rails

Dimensions

Length:  2130 mm / 84.0 in

Width:      700 mm / 27.5 in

Height:     990 mm / 39.0 in

Wheelbase

1365 mm / 53.75 in

Seat Height

775 mm / 30.5 in

Ground Clearance

140 mm / 5.5 in

Front Suspension

Telescopic fork with hydraulic damping and an offset wheel spindle

Rear Suspension

Woodhead-Monroe springs with hydraulic damping, later Armstrong and Girling, adjustable

Front Brakes

7.5 x 1.5 in drum

Rear Brakes

7 x 1 in drum
Front Wheel WM2 x 19
Rear Wheel WM2 x 19

Front Tyre

3.00 x 19 in, ribbed

Rear Tyre

3.50 x 19 in, studded

Rake

27°

Dry Weight

170 kg / 375 lbs

Fuel Capacity

19.3 L / 5.1 US gal

Fuel Consumption

3.9 L/100 km / 25.5 km/L / 60 US mpg
Braking  48 km/h / 30 mph - 0 30.5 ft / 9.3 m
Turning Circle 4.9 m / 16 ft
Top Speed 193 km/h / 120 mph
Colours Black/metallic silver, Deep blue/metallic silveer
Source Wikipedia

In 1965, the well-proven Venom was improved by Velocette designer Bertie Goodman with a special race kit complete with radically revised cylinder head, an Amal Grand Prix carburetor and reworked cam followers.

The following year this went into production as the Velocette Thruxton. Also known as the Venom Thruxton, this aimed to fill the gap left by the demise of the BSA Gold Star and was named after the Thruxton Circuit race track on a former wartime airfield in Hampshire. The Velocette Thruxton was a true racer, with a full race specification cylinder head that was gas flowed by hand to accommodate extra-large valves and a downdraught inlet port. The Amal carburetor was so large it required a distinctive cutaway in the bottom of the fuel tank, and race cams boosted performance to up to 120 mph (190 km/h).

As well as the traditional black-with-gold-lining finish, the Velocette Thruxton was also produced with an unusual blue frame, forks and seat and silver petrol tank with gold lining. In 1968 the Lucas magneto was phased out, and Velocette replaced it with coil ignition. A total of 1108 Thruxtons were built, but although it had more power than the Venom the Thruxton could not save Velocette. The company was wound up in 1968, and remaining stock sold until mid-1970. The Thruxton has gone on to become one of the most sought-after Velocette motorcycles today, however, and many private owners convert standard Venom models to the more valuable Thruxton specification.

At the 1964 Thruxton 500 endurance race, Velocette Venoms took the first three places in the 500 cc category, with winners Alan Harris and Howard German on a Stevens-entered machine finishing third overall in with the larger-capacity machines.

A specially styled, high-performance 'Thruxton' version of the Venom with high-quality equipment was announced in late 1964, and subsequently a Thruxton ridden by Motor Cycle journalist David Dixon and Joe Dunphy won the 1965 Thruxton 500 race, held at another disused airfield, the Castle Combe Circuit.

In 1967 two Venom Thruxton motorcycles, ridden by Neil Kelly and Keith Heckles gained first and second places in the Production TT, a category for road-based machines with limited controlled-modifications first staged at the Isle of Man in that year; Kelly also recorded the fastest lap at 91 mph. Prepared by Reg Orpin, workshop manager at London Velocette dealer L.Stevens, the winning motorcycle was far from standard, for as well as being in Thruxton trim, the valve gear included titanium tips to the pushrods and valve caps. A Norton Manx piston had been specially engineered at Velocette's Hall Green Workshops, and it had cam followers on needle rollers as well as light alloy timing wheels. It was nearly all for nothing, however, as Kelly failed to start and the rest of the field left him struggling to kick start the Venom. Orpin managed to start it just in time, and despite his poor start, Neil Kelly caught up with the other riders within three miles and went on to win the 500 cc class, recording 121 mph as he passed the Highlander speed trap.

Road Test

Chromium-plated trimmings are all very well, but they never add performance. With this in mind, Velocettes produce their Venom Special with most parts, such as the fuel tank, wheel rims and mudguards, which are normally plated, finished in enamel. Only mechanical difference is the use of a "waisted" rear hub instead of the Venom full-width type. The glass-fibre engine enclosure panels are retained.

Add the smooth charm of a beefy single, superb roadholding allied to exceptionally powerful brakes and the balance sheet shows an extremely desirable hogbus.

Likely to catch out first-timers unless the manufacturers' recommended drill was followed, cold starting usually required only one or two hefty swings on the pedal. On occasion, though, after a cold night in the open, the model required half a dozen swings before responding.

A single prod always produced results when the engine was warm.

BEEFY PUNCH

Pleasantly quiet mechanically, the engine produced beefy punch that encouraged early changing up—a bonus in built-up areas in view of the pleasantly sharp, but nevertheless loud, exhaust note. On the other hand, no one could complain of noise when the model was chuffing along at 30 mph in top.

Only low-speed indication of a sporty valve timing was erratic tick-over. To be reliable, idling had to be slightly fast and this sometimes caused noisy engagement of bottom gear.

Given its head on the open road, the Venom galloped to 80-plus with the rider sitting upright, or nudged 90 on downgrades. Half throttle gave a genuine 70 to 73 mph which could be maintained indefinitely without fuss or vibration and there was still ample performance left to cope with steep gradients in top gear.

The speedometer was commendably accurate, being no more than 1 mph fast. Super-grade fuel was used and prevented pinking unless the engine was abused.

Only indication of hard driving at the end of a long run was some oil drops from beneath the left-hand side panel where oil had been flung off the rear chain. A minor leak also developed during the test from the inlet side of the rocker box. Initially, the bottom gear of 11.24 to 1 seemed too high, but the illusion was soon dispelled when coping with the one-in-three test hill at MIRA. Ideally spaced, the other ratios matched engine characteristics perfectly. On the open road, second was usually held to 50 mph and third to 65 mph.

Light in operation, the clutch engaged the drive progressively, but after repeated use in dense city traffic it showed a tendency to drag. For this reason neutral was sometimes difficult to locate from bottom or second when at standstill.

Otherwise pleasantly smooth, the transmission produced a tremor, felt mainly through the left footrest and handlebar, when the engine was pulling very hard—such as on climbing a steep hill or restarting on a gradient.

Seat, footrests and handlebar positions gave a relaxed riding position up to 70 mph or so; then tall riders would have welcomed more forward lean to counteract wind pressure. A seat with deeper padding would have made long trips more comfortable.

With one exception, all controls were well positioned and light in operation. Exception was the combined horn button and dipswitch: this could not be operated without removing the left hand from the bar.

Race breeding showed on every bend through which the Venom swept. Light, utterly positive at all times—on all normal road surfaces, the steering was exemplary—sheer joy. Roadholding, too, was superb.

Well damped, both front and rear suspensions ironed out road shocks without pitching or weaving; even on the sharpest bumps, the suspension refused to bottom. The rear struts are adjustable for load and were normally set in the midway position for solo use; moving the units to the rear increases stiffness for passenger carrying. In short, the Venom Special was right in the top bracket for handling and a thoroughly reassuring model to ride under all conditions.

Among the most powerful on any big machine, the brakes lived up to their reputation—as the stopping distance shown in the performance panel indicates. They were equally as effective from maximum speed—smooth, progressively powerful and easily controllable. Throughout, the rear stopper squealed on hard application. Both brakes remained dry in wet weather.

For a machine of the Venom's performance, a headlight giving more range and spread would be an improvement. So would a louder horn.

Over the 1,200-mile test period, the model used a half pint of oil. Maintenance required was to adjust both chains once—a task hampered by the shrouding of the gearbox mounting front bolt by the clutch-cable stop.

Although it included a praiseworthy number of special tools, the kit omitted a spanner for the rear-wheel spindle nut.

Held in position by six screws, the glass-fibre side panels are easily detachable and enhance the appearance of the machine. A wipe with a damp cloth keeps them shiny.

Finished in blue-grey, the Venom Special must have a strong appeal to the rider who prefers to do without the glitter and be handsomely in pocket. He will own a machine of character, a rare quality in this mass-production age.