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1961 Matchless G12

1961 Matchless G12
650 Twin

Just prior to World War II, Triumph rocked the world with their seminal 500 Speed Twin, but the world had to wait for the war to end before the rest of the industry would have a chance to catch up. At war’s end, BSA was first to respond with their own 500cc vertical twin, the 1946 A7. Norton was next, followed by Matchlessfollowed in 1949, Norton with the Model 7, and Matchless with their G9. Of course, every Matchless came with a matching AJS back then (and they called them “Matchless”), in this case the AJS Model 20. Triumph being the first one to the party, they were also the first to start upping the ante in the horsepower-wars. In 1950, they bored and stroked out their own 500 to make the world’s first Triumph 650, the 6T Thunderbird, and most of the rest of the industry followed suit the best they could. Matchless and AJS countered in kind, bumping their 500’s displacement up to 650cc in 1958, along with new names, the Matchless G12 and the AJS Model 31. These were followed in turn by a larger version still, the 750cc Matchless G15 and AJS Model 33 in 1963.

1961 Matchless G12 SPECIFICATIONS

Model Designations, Matchless/AJS
Engine type
Bore & Stroke
Compression ratio
Oil capacity
Fuel system
Ignition System
Power output
Primary drive
Final drive
Suspension, front
Suspension, rear
Brakes, front
Brakes, rear
Frame type
Tire, front
Tire, rear
Dry weight
Fuel capacity
Fuel economy
Top speed
G12 / Model 31
Air-cooled OHV vertical twin
646cc / 39.4 ci
72mm X 79.3mm
Dry sump
2.5 L / 5.3 US pints
1 – Amal 389 1-1/8″
Lucas distributor & points
35 hp @ 6,500 rpm
Lucas 6V 12aH
1/2″ X 5/16″ single chain
Multi-plate, wet
4-speed, right-foot shift
5/8″ X 3/8″ chain, 96 links
AMC Teledraulic forks
Swing arm w/2 shocks
7 -n SLS drum
7-in SLS drum
Double cradle
3.25″ X 19″ Dunlop
3.50″ X 19″ Dunlop
396 lbs / 180 kg
4.5 US gal / 17 L
55 mpg / 23.4 km/L
95 mph