1959 Matchless 646cc G12

The last of the major British motorcycle manufacturers to offer a parallel twin, Associated Motor Cycles did not announce its own until the Earls Court Motorcycle Show of 1948, and even then production was for export only. Typed Model 20 (AJS) and G9 (Matchless), the two newcomers followed the established pattern of British parallel twins but were unusual in having an engine with a third, central, crankshaft main bearing. The new 498cc power unit was housed in the swinging-arm frame recently introduced on AMC's heavyweight singles.

For once there was a fair amount of variation between the two marques, which featured their own individual tanks, seats and exhaust pipes in addition to the customary badge and colour scheme differences. Progressively developed, the motor underwent a number of capacity increases, finally arriving at 646cc in the autumn of 1958 with the launch of the AJS Model 31 and Matchless G12. Well-finished, stylish and deservedly popular despite lacking the performance image of certain rivals, the AMC twins were much missed after their demise in 1966.

The private vendor purchased this Matchless G12 from Kettering Classic Motorcycles (AJS & Matchless OC) in March 2015. It has a replacement 1959 engine (from the equivalent AJS Model 31), which had been fitted prior to purchase.

Its previous owner had run the engine with the oil tap turned off, damaging the bores. Upon acquisition the vendor treated the engine to a full rebuild including a rebore, new pistons, new crankshaft bearings, and an Alton 12-Volt alternator conversion (invoice on file). A new clutch and primary chain were fitted also, and it should be noted that the machine retains the aforementioned anti-wet-sumping valve.

Uneven running was traced to a worn carburettor, and a new Amal instrument was fitted in October 2015. The Matchless has featured in Real Classics magazine on two occasions: in January 2016 (engine rebuild) and November 2022 (vibrations cured). (The mysterious engine vibrations were found to be caused by a loosened engine plate stud, located out of sight behind the crankcase.) The magneto was rewound in September 2016 and a new battery and tyres fitted in February 2018. Regular servicing has been carried out by the vendor, a retired RAF aircraft engine fitter, who states: "It has slightly sporty cam profiles so never idles smoothly, but can really motor if you hang on to the revs long enough." He describes the machine as not concours but very tidy and in great condition, capable of eating up the miles easily.

Ridden to Bonhams' premises in time for the sale, the Matchless comes with a huge file of servicing and maintenance paperwork together with the vendor's own very useful operating and usage guidance (inspection essential). Additional documentation includes a V5C Registration Certificate; AJS OC dating letter; previous-owner correspondence; expired MoTs and tax discs; sundry invoices; and a BMS photocopy maintenance and instruction manual. A spare pair of silencers is included in the sale.
Key not required