Ducati 450 R/T

The Ducati 450 R/T (road/trail) is a 436 cc (26.6 cu in) single cylinder bevel drive desmodromic SOHC motorcycle produced by the Italian manufacturer Ducati from 1971 to 1974. Initially produced at the request of the American importers Berliner Motor Corporation[4] as a pure motocross machine exclusively for the American Market, only a few hundred machines were made of this type.[5] It is the only motocross bike to use desmodromic valves.[6] An optional street equipment kit was available.[7] From 1972 it was produced for the European Market as a street legal on/off road machine,[8] which was sometimes known as the 450 T/S.[9]

Ducati 450 R/T
Ducati 450 R/T
ManufacturerDucati
Production1971
ClassOn/off road
Engine435.66 cc (26.586 cu in) Air-cooled bevel drive SOHC single cylinder four stroke
Bore / stroke86 mm × 75 mm (3.4 in × 3.0 in)
Compression ratio9.3:1
Power36 bhp (27 kW) @ 6,500 rpm
TransmissionMultiplate wet clutch, 5 speed
Frame typeHalf-duplex cradle
SuspensionFront: telescopic forks
Rear: swinging arm
BrakesDrum front & rear
TyresFront: 300x21
Rear: 400x18
Wheelbase1,450 mm (57 in)
DimensionsL: 2,180 mm (86 in)
W: 930 mm (37 in)
H: 1,200 mm (47 in)
Seat height790 mm (31 in)
Weight124 kg (273 lb) (dry)
Fuel capacity10 L (2.2 imp gal; 2.6 US gal)
Footnotes / references
[1][2][3]

Total production was around 460 machines.[10]

History

American desert racers Doug Douglas and Jim McClurg had won the inaugural Baja 500 on a modified 350 Ducati desmo in 1969.[7] This prompted US importer to request a 450 off-Road racer to compete with the successful BSA B44 Victor.[5] Ducati employed 1966 Italian scrambles champion Walter Reggioli to develop the new bike.[11]

The tank, mudguards and side panels were made of bright yellow fibreglass. Even with rubber-mounting, engine vibration and frame-flex caused the components to crack.[12]

A street equipment kit was available which consisted of front and rear lights, wiring and handlebar switches. With the kit fitted the bike was not street-legal as it had no brake light, horn or silencer.[13]

The engine was set too far back for the short wheelbase making the machine difficult to turn.[5] With under-damped suspension and a dry weight of nearly 300 lb (140 kg),[7] American riders preferred the new lightweight two strokes and the bike was only imported for a year.[5]

At the 1971 ISDT held on the Isle of Man, the Italian team used R/Ts, including three fitted with demo 350 cc engines.[14] These machines had a modified steering head angle, high level twin silencers and a centre stand to ease changing wheels when punctured.[8]

In 1972 the bike was offered with full street equipment. This included lights, horn, instruments, alternator, coil ignition and an ignition switch mounted in the headlight shell. A low level exhaust and Silentum silencer, as used on the Mark 3, was fitted. In 1974 electronic ignition were fitted.[15]

Technical details

Engine and transmission

The single cylinder bevel drive OHC engine was of vertically spilt unit construction[16] and had an alloy head and alloy barrels with austenitic liners.[17] Ball bearings were used in the main bearings and roller bearings for the big end.[18] The head used desmodromic valves. (A system where the valves are positively closed by extra lobes on the cam and levers rather than by a more conventional springs).[19] Bore and stroke were 86 mm × 75 mm (3.4 in × 3.0 in) giving a displacement of 436 cc (26.6 cu in). Compression ratio was 9.3:1. and the claimed power output was 36 bhp (27 kW) @ 6,500 rpm.[20] A decompressor was fitted to aid starting and also as a method of stopping the engine as no ignition switch was fitted.[12][13]

Fuel was delivered by a 29 mm Dell'Orto UHB carburettor.[8] Wet sump lubrication was used.[3] Ignition was initially by flywheel magneto. This was changed to a battery and coil in 1972 and electronic ignition was fitted in 1974.[21]

The primary drive was by helical gears to a multi-plate wet clutch[22] to a 5 speed gearbox.[3] Chain drive took power to the rear wheel.[23]

Cycle parts

The 450 R/T used a newly designed single downtube frame that shared several features with the 750 GT.[24] Front suspension was by 35 mm (1.4 in) diameter[25] telescopic forks made by Marzocchi. Based on a design by Ceriani, they offered 7 in (180 mm) of travel. A swinging arm was used on the rear with twin non-adjustable shock absorbers. The top of the shock absorbers could be attached in four different positions to adjust the rear suspension geometry.[12] 3-way adjustable shocks were fitted from 1972.[8]

Brakes were 158 mm (6.2 in) diameter drums front and rear, the front being the same as the unit used on the Monza Junior.[26] Wire wheels were fitted with Borrani alloy rims,[12] and 400x21 front and 300x18 rear tyres.[27]

350 R/T

A few 350 R/Ts were produced in 1971 and were fitted with the 350 desmo engine.[28] In 1974 the R/T was available in the domestic Italian home market fitted with the non-demo engine of the Mark 3.[15][29]

References
  1. Cycle World 1971, p. 41.
  2. Falloon 2016a, pp. 209–217.
  3. Walker 2003, pp. 219–221.
  4. Falloon 2006, p. 48.
  5. White 2019.
  6. Early Years Of Motocross.
  7. Bonhams.
  8. Verrini.
  9. Walker 2003, p. 224.
  10. Falloon 2016a, p. 281.
  11. Aynsley 2020.
  12. Bartlett 2013.
  13. Cycle World 1971, p. 39.
  14. Falloon 2016a, pp. 215–216.
  15. Falloon 2016a, p. 216.
  16. Walker 2003, p. 50.
  17. Walker 2003, p. 40.
  18. Walker 2003, pp. 34, 52.
  19. Cameron 2014.
  20. Falloon 2016a, p. 217.
  21. Walker 2003, pp. 209, 216.
  22. Walker 2003, pp. 72, 74, 103.
  23. Walker 2003, p. 103.
  24. Falloon 2016a, pp. 209–210.
  25. Falloon 2016a, p. 211.
  26. Falloon 2016a, pp. 211, 217.
  27. Cycle World 1971, p. 40.
  28. Falloon 2016b, pp. 107–108.
  29. Ducati Classics.

Bibliography
  • Aynsley, Phil (April 2020). "The Ducati 450 R/T - inspiration for the firm's modern day street scramblers". Classic Bike – via www.pressreader.com.
  • Cameron, Kevin (25 April 2014). "Why Does Ducati Stick With Desmodromic Valve Operation?". Cycle World.
  • Bartlett, Dale (24 October 2013). "GP's Classic Steel #69: 1971 Desmo Ducati R/T 450". pulpmx.com. Retrieved 15 October 2021.
  • Falloon, Ian (2006). The Ducati 750 Bible. Veloce Publishing Ltd. p. 46. ISBN 1-84584-012-7.
  • Falloon, Ian (18 March 2016). The Book of the Ducati Overhead Camshaft Singles. Poundbury, Dorchester: Veloce Publishing Ltd. ISBN 978-1-84584-566-7.
  • Falloon, Ian (July 2016). The Complete Book of Ducati Motorcycles: Every Model Since 1946. Minneapolis, MN: Motorbooks. ISBN 978-0-7603-5022-5.
  • Verrini, Michele. "DUCATI RT | Ducati rt 450 ricambi e accessori". www.rtducati.com. Retrieved 16 October 2021.
  • Walker, Mick (2003). Ducati Singles Restoration. MotorBooks International. ISBN 978-1-61060-919-7.
  • White, Tom (3 February 2019). "Classic Motocross Iron: 1971 Ducati 450 R/T Desmo". Motocross Action Magazine. Retrieved 15 October 2021.
  • "250, 350 And 450 Scrambler". Ducati Classics. Retrieved 2 October 2021.
  • "1972 Ducati R/T 450 Desmo Engine no. 454471". Bonhams. Retrieved 15 October 2021.
  • "Ducati 450 R/T road test". Cycle World. September 1971. pp. 38–41 – via Ye Olde Cycle Shoppe.
  • "Motorcycles". Early Years Of Motocross. Retrieved 15 October 2021.
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