Mountain Cub (T20SM/T20M)

Mountain Cub (T20SM/T20M)

The Mountain Cub was possibly the very first Triumph motorcycle to be classed as a 'Trail' bike and an intriguing story about how it came about is in the book 'Triumph in America' written by Lindsay Brooke and David Gaylin.

Seemingly Edward Turner was over in the USA considering winding down production of some of the special 'made for USA' Tiger Cub models when three senior American Triumph staff members built an on/off road Cub with which to take on the lightweight Japanese trail bikes that were selling quite well over there. The Cub was based on the T20SC with some elements of the TR20 and they named it the 'Mountain Cub'.

 

An order for 400 machines made E.T. take more of an interest and the first example of the new model was delivered in October 1963. Eventually 3000 went to the west coast of the USA, 1500 to the east coast; and a total of over 6000 Mountain Cubs were sold all over the world.

The T20SM and T20M were basically the same model with the exception that the SM had both side and centre stands whereas the M had neither. They had the T15 Terrier petrol tank, speedometer (tachometer an option), Energy Transfer Ignition and lights, wide-ratio gear cluster, folding footrests, heavyweight forks (adjustable rear shocks an option), trials tyres, crankcase undershield, upswept handlebars and a small triangular shaped tool box.

The petrol tank badge was a particularly nice item with black writing on a gold and chrome background or white lettering on a Grenadier Red and chrome background.

It appears the Mountain Cub was first listed as the T20SM but by late 1965, the sales brochures just mentioned the T20M. However the factory records continued to refer to T20SM as well as 'Export' and T20M.

Colours for the T20SM & T20M 1964-67

1964:

Crystal Blue and Silver Sheen

1965:

Hunting Yellow

1966/67:

Grenadier Red and Alaskan White

The colours were all bright, and it's said they were so to make the machine stand out whilst trail riding so they could be easily seen.

Specifications

Production T20SM

Started:

22nd October 1963

Finished:

30th July 1968

Numbers:

95152 to 9849

(not continuous at all)

Production T20M

Started:

30th March 1966

Finished:

27th January 1967

Numbers:

662 to 8933

(not continuous at all)

Production T20M (for WD)

Started:

12th March 1970

Finished:

6th May 1970

Numbers:

10002 to 10050

(not continuous - some engines were put in earlier frames)

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

Power:

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

Carburettor:

Amal Monobloc 376/314

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:

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) (up to 1965)

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

Electrics

Type:

Lucas Energy Transfer

Voltage:

6

Charging Type:

Alternator / Rectifier

Ignition Timing:

16° BTDC static. 36° fully advanced

Points Gap:

0.014in - 0.016in

Spark Plug:

Champion L7 or equivalent

Spark Plug Gap:

0.020in