Sports Cub (T20S)

Sports Cub (T20S)

Cubs Sweep the "Scottish" proclaimed the headline in 'The Motor Cycle' and unsurprisingly, given the success the Tiger Cub was having in the field of sporting and competition events worldwide, a new model, the T20S was released in 1959. Further building on the formula of the T20C model, the T20S (Sports Cub) was to change people's perception of lightweight motorcycles and set a trend that's still prevalent today. Lightweight go anywhere trail, off road and adventure bikes.

The T20S could be ordered in three different guises, but all had a high level exhaust that routed outside the subframe, a crankcase undershield, heavyweight (internally sprung) forks, energy transfer ignition system enabling the machine to be run without a battery, quickly detachable headlight (if fitted), high performance valve springs, large inlet valve and the 'R' camshaft. A side stand only was fitted (no centre stand).

Standard/Road specification with lights, road tyres, small toolbox, 'D' shaped single instrument speedometer or round speedometer and tacho, 9:1 piston, the 'R' camshaft, close-ratio gears, 15/16 inch Amal Monobloc 376/272 or Zenith carburettor and silencer.

 

Trials specification, no lights, trials tyres, optional speedometer, 7:1 piston, 'R' camshaft, wide-ratio gears, silencer and 7/8 inch Amal Monobloc 332 or Zenith carburettor.

 

Scrambles/Racing specification, this machine was fitted with no lights, speedometer, horn or number plates although a tachometer was an option (on later models). It had full scramble tyres, 9:1 piston, the 'R' cam, close-ratio or extra close-ration gear cluster, exhaust pipe extension (replacing the silencer) and a Monobloc 376/217 carburettor with remote float chamber and larger size main jet.

A two-tone colour scheme (1959) was standard of Ivory and Azure Blue (UK, USA and other markets) and Aztec Red (USA). Same for 1960 with the exception of the dropping of the Aztec Red livery.

 

1961 models were in Ruby Red and Silver Sheen (Ruby Red also known as Bright Amaranth Red for the USA).

Specifications

Production

Started:

6th December 1958

Finished:

17th January 1961

Numbers:

48139 to 74133

(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:

9 : 1

7 : 1 on Trials spec

Power:

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

Carburettor:

Various depending on spec.

15/16 inch Amal Monobloc 376/272

Zenith

7/8 inch Amal Monobloc 332

Monobloc 376/217 carburettor with remote float chamber

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, twin shock absorbers

Front Wheel:

19 inch (WM1 rim)

Rear Wheel:

18 inch (WM2 rim)

Front tyre:

3.00 x 19

Rear tyre:

3.50 x 18

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)

Electrics

Type:

Lucas Energy Transfer

Voltage:

6

Charging type:

Alternator / Rectifier

Ignition Timing:

16° BTDC static. 40° fully advanced (9:1 compression)

8° BTDC static. 28° fully advanced (7:1 compression)

Points Gap:

0.014in - 0.016in

Spark Plug:

Champion L5, L7, LA11 or equivalent

Spark Plug Gap:

0.020in