Velocette Thruxton

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Velocette Thruxton
Velocette Thruxton 500 cc 1965.jpg
Manufacturer Velocette
Also called Venom Thruxton
Production 1965–1971
Predecessor Velocette Venom
Engine 499 cc (30.5 cu in), OHV air cooled single
9:1 compression ratio[1]
Amal 5GP2 13/8 carburettor[1]
Top speed 180 km/h (110 mph)[2]
Power 31 kW (41 bhp) @ 6,200 rpm[3]
Brakes front drum, 7.5 inch John Tickle 2LS,[1] rear drum
Wheelbase 139.1 centimetres (54.75 in)
Seat height 30.5 inches[1]
Weight 180 kg (390 lb) (dry)
Fuel capacity 4.5 gallons[1]
Oil capacity 4 pints[1]
Fuel consumption 60mpg at 65mph[1]

The Velocette Thruxton was a sporting motorcycle produced by Velocette between 1965 and 1971. Revealed at the 1964 Earls Court Show, it was the final development of Velocette's antiquated pushrod single, the Venom.[4]

Sometimes referred to as the Venom Thruxton or simply Thruxton, some surviving examples could be 'upgraded' replicas based on the Venom or Viper, as many parts in the range were interchangeable. Due to the high values involved and possibility of fakes, a register was established by a member of the Velocette Owners Club, using production data of engine and frame numbers acquired after the factory closure, to enable owners and potential buyers to confirm provenance when selling and buying.[5]

The Thruxton ceased production only when the company folded in 1971.[3]

Development[edit]

An optional cylinder head for the Venom became available for racers in 1964;[6][7] a Venom equipped with this revised cylinder head took first in its class at that year's Thruxton 500, a 500-mile (800 km) endurance road race. Veloce introduced the Venom Thruxton production model in 1965 with an advertised 41 horsepower at the crankshaft. Period tests clocked it at 110 mph (180 km/h) without race tuning.[2]

The well-proven Venom was improved by Velocette designer (and owning-family member) Bertie Goodman with rearward placed footrests having brake pedal and remote gear-change linkage to suit, close-ratio four speed gearbox, alloy rims, twin-leading shoe front brake and 'clip-on' handle bars. The engine gained a race specification cylinder head to accommodate extra-large valves, a downdraught inlet port and an Amal 5GP2 13/8 bore carburettor[1] with extended inlet tract which was so long it required a special cut out in the rear of the fuel tank. The upgraded engine delivered 41 brake horsepower (31 kW), 5 bhp more than the Venom.[3]

It was important for eligibility in endurance races such as the Thruxton 500 that competing motorcycles were genuine production machines, but although the Velocette Thruxton was sold in a road-going version, it was really targeted at the racing fraternity.

No more than 1,108 Thruxtons were manufactured before the company collapsed in 1971.[8]

Racing success[edit]

Although named after the Thruxton 500 endurance race, for 1965 the race was actually held at another disused airfield, Castle Combe, and was dubbed "The Motor Cycle 500-miler".[9] The early-version Velocette Thruxton, ridden by Motor Cycle journalist David Dixon and racer Joe Dunphy, won the 500cc category.[9]

In 1967 two Thruxtons, ridden by Neil Kelly and Keith Heckles gained first and second places in the 500cc Production TT, the first time a production-machine event had been staged at the Isle of Man with Kelly also recording the fastest lap at 91 mph.[3]

Further development[edit]

Instrumentation of a Velocette Thruxton motorcycle

Geoff Dodkin and L.Stevens were two well-known specialist motorcycle retailers in the London area offering mechanical upgrades and cycle customising parts backed by their own race experiences. These included nimonic valves,[1] larger lightweight aluminium oil and fuel tanks, seats, smaller megaphone silencers and an alloy top yoke.

The Avon race fairing (made by Mitchenall Brothers) was introduced in 1964 in time for the June Isle of Man TT Races[10] but the transparent, aerodynamic 'nose-cone' extending over the front race number plate area was soon 'outlawed' by the ACU, the UK motorcycle race-organisation governing body.[11]

This led to the fairing being modified for a headlamp and offered for road use, complete with transparent nose cone.[11]

The Velocette Thruxton Veeline version was one of the first to be available to the public, coming from the factory finished to match the standard Thruxton colour scheme in blue and silver[1] or the optional black and silver.

Last development[edit]

During the last years of Velocette production, in 1968 American entrepreneur Floyd Clymer conceived the Indian Velo 500, a limited-production run of updated machines using mainly Italian cycle parts. Clymer had negotiated supply of separate Velocette engines and gearboxes, including some Thruxton engines.[12]

References[edit]

  1. ^ a b c d e f g h i j The Classic Motor Cycle, Classic Road Tests, July 1996, reprinted in Walneck's Classic Cycle Trader, Feb 12-15, 2010. Accessed 2013-07-08
  2. ^ a b Siegal, Margie (January–February 2013). "Velocette Thruxton: A Tale of Two Fishtails". Motorcycle Classics. 8 (3). Retrieved 2013-01-31. 
  3. ^ a b c d Kemp, Andrew; De Cet (2004). Classic British Bikes. Mirco. Bookmart Ltd. ISBN 1-86147-136-X. 
  4. ^ Motor Cycle, 19 November 1964. 'Earls Court Show Guide'. p.861/2. "High spot of the latest Velocette presentation is the Venom Thruxton 500—one of the Venom family, obviously, but trimmed for racing." Accessed 2013-08-17
  5. ^ The Classic Motor Cycle July 1996, p.39 Register that Thruxton Accessed and added 2014-06-27
  6. ^ Motor Cycle 15 October 1964 pp.698-699 Velocette 1965 Range. Super-Speed Venom. "Scintillating news from Velocettes about the 1965 range is not of a machine as such. It concerns a catalogued extra for thew 499 cc Venom Clubman—an ultra-high-performance cylinder head which, in conjunction with a 13/8"-choke Amal GP carburettor, is claimed to give the Venom a potential of around 135 mph! Intended for racing, the new cylinder head is an individually made tool-room job rather than a production item...When the cost of the head and carburettor, plus specially modified fuel and oil tanks, is totalled, the extras bill comes to around £64.". Accessed 2015-04-22
  7. ^ MSS to Thruxton, by Rod Burris at Google books Retrieved 2015-04-22
  8. ^ "Velocette 1965 Thruxton 500cc". Retrieved 2008-11-16. [dead link]
  9. ^ a b Motor Cycle 29 July 1965 pp.138-140 Motor Cycle 500-miler. "Senior Class (500 cc)—1. P.J.Dunphy and D.J. Dixon (499 Velocette), 230 laps, 6h  19m 45s, 66.79mph". Accessed 2015-04-22
  10. ^ Motorcycle Mechanics, November 1964, "After their successful introduction in the Isle of Man, the new Avon fairings are on sale to the general public.... The fairing is available for Cotton Aermacchi Manx 7R and G50 machines". Accessed 2013-08-05
  11. ^ a b Motor Cycle 23 September 1965 Brighton Show Round-up, p.431 "So that's what happened to those nose cones the ACU frowned on. The Mitchenall fairing attached to the Thruxton Veeline on Velocette's stand sported that see-through bulge in front of the headlamp" and p.432 "AHA! Mitchenall's have found a way of using up those banned clear-plastic racing nose cones. The mighty Velocette Thruxton five-hundred was dressed in an Avon fairing of out-and-out racing ancestry—yet it retained its headlamp, flush-mounted in a flat-front bulkhead and shining out through one of those cones. Crafty!" Accessed 2013-08-07
  12. ^ The Classic Motor Cycle July 1996, p.39 Register that Thruxton. "In July 1968, Floyd Clymer bought a Thruxton engine...records show that 26 more engines were sold to Clymer in November 1968, with a final 18 the following January". Accessed and added 2014-06-27

External links[edit]