Trials & Scrambler (TR20/TS20)

Trials & Scrambler (TR20/TS20)

The brainchild of works rider Jim Alves, the trials version of the Tiger Cub had debuted in 1957 as the T20C and was steadily improved year by year until in 1962. A development of the T20SS model led to the TR20 and TS20 Tiger Cubs from 1962 until 1965.

They were extremely specialised machines. Even being described as 'Works Replicas' by the factory and enabled the public to buy, as near as possible, the same Tiger Cub as those built for the factory riders to use in competition.

 

Roy Peplow’s landmark victory in the Scottish Six Days Trial in 1959 emphatically demonstrated the Tiger Cub was easily capable of winning major events, and the Triumph factory was not slow in answering the call for similar machines to be made available to one and all.

Both models had a high level exhaust system, crankcase undershield protector, single seat, polished alloy mudguards, sealed wheel bearings, wide handlebars (braced on the TS20) and a shortened left footrest bracket carrying the rear brake pedal. No lights, toolbox, side or centre stands, even the heavyweight front forks were devoid of covers between top and bottom yokes.

The rear subframe was altered on the right-hand side to allow the exhaust pipe to route inside it and soon after production began, double gusseting strengtheners appeared on the front frame under the headstock. The T15 Terrier petrol tank was fitted along with a 'Volks' type air cleaner to the carburettor. A optional front competition and rear number plate was listed.

The TR had a 'D' shaped speedometer mounted on the top yoke and a bulb horn (neither fitted on the TS), and rearward facing footrests (standard ones on the TS). It was also fitted with the wide-ration gear cluster whereas the TS20 had the extra close-ratio item.

 

Interestingly, some early engines were numbered T20SST.

The 1962 models had the top-mounted points assembly before changing to the side-points type as the engines became available. The same as all the other Cubs, engine upgrades and improvement updates were used as soon as they came on line. In 1965, front forks with the springs on the outside of the stanchions were fitted.

Colour scheme for 1962/63 models was Burgundy and Silver Sheen.

 

For 1964/65 it was Hi Fi Scarlet and Silver Sheen.

Specifications

Production TR20

Started:

24th March 1962

Finished:

5th February 1965

Numbers:

85148 to 1868

(not continuous)

Production TS20

Started:

11th April 1962

Finished:

5th February 1965

Numbers:

85323 to 1870

(not continuous)

Engine

Type:

Single-cylinder OHV, unit construction

Capacity:

199cc (12.1 cu in)

Bore / Stroke:

63mm (2.480in) x 64mm (2.520in)

Compression:

7 : 1 (TR20)

9 : 1 (TS20)

Power:

16bhp (12.1 kW or 16.2 PS) @ 6700 rpm

Carburettor:

Amal Monobloc 374/44 (TR20)

Monobloc 376/272 (TS20)

Camshaft:

'R' cam - valve clearances In 0.002in : Ex 0.004in (cold)

Clutch:

Wet multiplate

Gears:

4

Cycle Parts

Front Suspension:

Telescopic forks, hydraulic damped

Rear Suspension:

Swing-arm with twin shock absorbers

Front Wheel:

21 inch (WM1 rim)

Rear Wheel:

18 inch (WM3 rim) (TR20)

19 inch (WM2) (TS20)

Front tyre:

2.75 x 21

Rear tyre:

4.00 x 18 (TR20)

3.50 x 19 (TS20)

Brakes:

5.5 in dia. Single leading shoe drum front and rear

Petrol Tank:

2.625 UK gallons (3.15 US gallons or 11.92 litres)

Oil tank:

2.75 UK pints (3.3 US pints or 1.56 litres)

Gearbox:

1/3 UK pint (0.4 US pints or 0.19 litres)

Primary Chaincase:

1/3 UK pint (0.4 US pints or 0.19 litres)

Front Fork:

1/4 UK pint (0.3 US pints or 0.14 litres) (up to 1965)

1/3 UK pint (0.4 US pints or 0.19 litres) (1965)

Electrics

Type:

Lucas Energy Transfer

Voltage:

6

Charging Type:

Alternator / Rectifier

Ignition Timing:

12° BTDC static. 32° fully advanced (TR20)

20° BTDC static. 40° fully advanced (TS20)

Points Gap:

0.014in - 0.016in

Spark Plug:

Champion L7 or equivalent (TR20)

KLG F80 or equivalent (TS20)

Spark Plug Gap:

0.020in