From our Old Bike Archives – Issue 89 – first published in 2020.
Story: Peter Laverty • Photos: Old Bike Australasia
While it appears that the single cylinder Matchless – in sizes from 250cc to 500cc – changed little in its more than three decades as part of the model range emanating from the factory in Plumstead, London, there were subtle refinements. Of course, the range of singles expanded somewhat when AJS became part of Matchless Motorcycles (Colliers) Ltd in 1931, and for a while the AJS and Matchless products retained their own identities and designs. But gradually a blending of the two occurred and the pair became badge brothers thereafter.
What became known as the Matchless ‘G’ range of overhead valve singles first appeared in mid 1935 with two 350cc models; the G3 road model and a trials version called the Clubman Special. In short order the range expanded to include a 250 (the G2) and a 500 in both single exhaust port and twin exhaust port (the G80).
1937 was a big year for Matchless, and after acquiring the manufacturing rights to Sunbeam motorcycles from the chemical giant ICI, the company name was changed to Associated Motorcycles Ltd – or AMC. Also in 1937, full enclosure of the overhead valve gear became standard on the AJS range, but curiously the Matchless 250, 350 and 500 ohv singles retained exposed hairpin or coil springs for 1937and 1938. This saw a new aluminium rocker box casting appear on the AJS models, which was bolted to the iron cylinder heads, and with rockers, valve springs and valve stems now under this neat cover, it meant that positive lubrication could be applied to these moving parts, and that lubricant remained inside; at least, that was the theory. In the bottom end, heavier flywheels, aimed at increased smoothness at low revs, were fitted to the 500s.
A big choice
As displayed at the all-important Earls Court Motorcycle Show in November 1938, AJS and Matchless revealed a 30-strong range across the 250, 350 and 500cc models – five variants of each in both brands. That’s just the OHV models; there were also side-valve models in 250cc and 500cc. In addition, there was a side valve 1000cc V-twin in both AJS and Matchless guise.
Top of the Matchless 350s and 500s were the Super Clubman models, sporting the a completely redesigned cylinder head, with the head itself, rocker box and valve spring chambers formed in one iron casting, along with increased cooling fin area. This was claimed to not only cure oil leaks, but significantly improve the life of components such as rockers and valves, which now ran in oil rather than being exposed to the elements.
For the Super Clubmen models, the cylinder heads were polished with larger inlet and exhaust ports, and higher compression pistons. Both the 500 engines were fitted with a compression plate which could be removed when petrol-benzol fuel was used. Aimed at the amateur racer, the Super Clubman also featured a closer-ratio gearbox, lighter mudguards and larger section rear tyres; features which were not found on the standard Clubman. An upswept exhaust pipe was standard on the Super Clubman but a low level pipe was available as an option. The Super Clubman was officially known as the G90, and featured seven-inch brake drums turned from steel, rather than being pressed out, with a quickly-detachable rear wheel.
Common across the 350cc and 500cc range was the duplex semi-cradle frame that had been used on the Matchless models throughout the ‘thirties. This frame, with twin front down tubes bolted to separate bottom rails and through the front of the crankcase, gave way to the single down-tube frame that appeared on the WD bikes and continued thereafter. The Super Clubman and Clubman 500s also benefited from the excellent girder front forks, which included additional ‘check springs’ between the top and bottom links, which were originally developed for the 350cc AJS R7 production racer.
For the 1938 models, one bugbear that was eliminated was the need to disconnect the wiring when removing the petrol tank. By redesigning the centre section of the tank itself, the instrument cluster (comprising Ammeter, a clock, trouble lamp and the main switch for lighting) and its base plate could now pass through the bottom of the tank intact, eliminating tedious and unnecessary work.
The new models were enthusiastically received, but by late 1938, Britain had bigger issues to consider. As war clouds gathered, motorcycle manufacturers were readied for conversion to wartime production, so the new AMC range was very short lived. In fact the only product to emerge from Plumstead from 1940 was the 350 Matchless, initially in girder fork form as the G3WO, and later with AMC Teledraulic telescopic forks as the G3/L.
A rare bird
From this it can be seen that the earlier G80 models were scarce in their day, particularly the up-spec and more expensive Clubman and Super Clubmen models. They’re even rarer now, which makes the appearance of Ken Robinson’s 1939 G80 model at events such as the 2020 Orange Country Rally a cause of much interest.
Ken and his wife Cathy, an enthusiastic pillion, live not far from Orange at Oberon, where Ken is very well known for his extensive collection and comprehensive knowledge of motorcycles in general, which extends from the early English models through to the Ducati era. Ken bought the Matchless in Canberra around 2012, in a state that he describes as “Complete but loosely put together”. That ‘loose’ assembly process had involved placing a 1948 engine in the frame, which in Ken’s eyes was the first thing to get right.
The ‘project’ sat around for five years while Ken gathered data and various parts, but the major breakthrough came when on a visit to the Goulburn Swap Meet he discovered the basis for the correct engine. It was however, just a start to a more lengthy process, as the engine transpired to be the bottom end (crankcases, crankshaft, cams etc.) from a 1939 engine, and to facilitate the process Ken decided to fit the barrel and head from the 1937/38 design, with separate detachable covers for the coil valve springs.
“The 39 model had the ‘monoblock’ head which had the rocker box cast in with the iron head, with end caps over the valves and a separate cover over the tappets. To get the bike up and running I put the engine together with a 37/38 top end that I found on eBay, which had the rocker box made up of several sections, and had it on club registration for two years. Then I found the correct head, which is a fairly rare item, and I am in the process of fitting that, along with the matching barrel. The 1939 head retained the hairpin valve springs on the 500 while the smaller engines used coil springs.”
That ‘one-piece’ head/rocker box is known to be extremely heavy, and to be a tricky proposition to work on. The hairpin springs are a very snug fit inside the casting, and Matchless even put out a special tool to assist in their fitting. A common modification was to replace the hairpin springs with coil springs which were easily obtainable even back then and a much simpler proposition to fit and/or remove, although the hairpin springs were reckoned to be stronger and more durable.
The use of the QD rear wheel, where the brake drum and sprocket remain in place when the axle is removed to allow the wheel to drop out, means the usual British system of driving the speedo via a gearbox from the rear wheel is not possible. Consequently, these models, such as Ken’s, have the speedo driven from the front hub; an item with different appearance and finning to the normal item, and one that is also a challenge to locate these days.
These pre-war AMC models were renowned for the quality of the finish, and Ken’s restoration mirrors this, with deep lustrous black enamel and gleaming chrome plating. “The bike was originally in maroon/chrome for the petrol tank, but the model also came in black with silver striping so I decided to do it like that. A few years back a very similar bike appeared at the AJS/Matchless rally here in Oberon – a twin exhaust port 500 G90. It’s the only other one I have seen.”
The judges at the 39th Orange Country Rally (completed just days before Australia went into lockdown with the Covid-19 pandemic) thought Ken’s Matchless a worthy recipient of the prestigious Bike of the Rally Award. Ken, Cathy and the G80 made a fine sight (and sound) motoring through the hills over the two days of the event; a big single truly in its element.
Specifications: 1939 Matchless G80 Clubman
Engine: Single cylinder overhead valve
Bore x stroke: 82.5mm x 93mm
Compression ratio (Std): 5.9:1
Carburettor: Amal
Ignition: Lucas magneto
Lighting: 6 Volt Lucas generator
Lubrication: Matchless reciprocating oil pump
Transmission: Burman 4-speed gearbox with chain primary drive.
Instruments: Ammeter, optional clock and speedo.
Frame: Steel tube duplex, bolted up.
